What year?
I’m really not that old (cetainly don’t feel it), but my top three would have to be:
-
The Doors - September 1969
No, he didn’t whip it out, but witnessing an ad lib to ‘The End’, while on mescaline, at the end of a fantstic show, was nothing short of amazing. -
Pinkfloyd - March 1973
The ‘Dark Side of the Moon’ tour. Floor seats, girlfriend at my side. Wow! -
Jethro Tull - February 1972
Aqualung tour. Heard the music in my head for the next 72 hours. Now, I can’t hear a thing. What? Speak up!
Frank Zappa, Beacon Theater, NY, about two years before he passed on
Billy Joel, Madison Square Garden, NY, 1986
Phish, Albany, NY
Simon and Garfunkel, Central Park, NY, 1981
Cafe Tacuba, Guelaguetza amphitheater, Oaxaca, Mexico
Although, upon rereading the OP, I see rock concert was not specified. So I’d have to consider a hundred shows, from Art Blakey to the Waverly Consort. But I think that belongs in a different thread.
LIVE AID. I went with a group of friends, and my then bf. We listened to the radio around the clock, in order to find out when tickets were going on sale. We got lousy seats, but security in the crowd was non existant. I spent the last five hours three rows back from the front of the stage, marvelling at Jimmy Page and Robert Plant, Mick and Tina (yes I saw the look on her face when he ripped off her skirt), Patti Labelle’s mike cut off halfway into her performance of “Over The Rainbow” and I could still hear her belting it out while sweating profusely, and rolling around the stage. It was a very good day…
I was at Lemonwheel & I’ll second that it was a great weekend of music. The “Harry Hood” they played was a thing of beauty. I’ve seen a ton of Phish shows, and that was probably my favorite…maybe my favorite concert of all time.
Kotke is amazing to watch & listen to. I also had the pleasure of actually seeing Leon Redbone just last night. I challenge anyone to see him perform & not leave the place smiling. He was simply amazing.
Hmm…I haven’t really pegged down that “Greatest show ever” yet. I did have the chance to join Gary “U.S.” Bonds on stage (playing bass) a few years ago & that always stands out for me as my favorite concert, but for different reasons.
Queensryche on their “Promised Land” tour was amazing too. As was the one time I saw Morphine and the many times I’ve seen The Screamin Cheetah’ Wheelies.
Peter Gabriel - the Us tour
Chris Isaak - any
Sting - Dream of Blue Turtles tour
Beck - solo acoustic tour before the release of the next to last album
Um, and there’s a really great one that was fairly recent (last two or three years) that I’m totally spacing on. I can remember leaving the show and just being blown away but can’t remember who it was…
I’m hard pressed to pick a single one, but some of the highlights include …
Depeche Mode - October 29, 1993 at the Rosemont Horizon (now Allstate Arena) in the Chicago area. Devotional Tour.
VNV Nation - November 16, 2001 at the Vic in Chicago. Futureperfect Tour.
Hate Dept. - March 3, 1999, don’t even remember the venue. Some bar. There were only about 10 people in the crowd, but they played like there were 10,000 - absolutely fantastic.
Chemical Bros. with The Orb - April 24, 1997 at the Aragon ballroom in Chicago. I’m not a huge fan of either act, but that was a HELL of a show. I had blisters on my feet from walking all day before the show - the energy of the bands made me dance the entire night anyway. When I got back from the show, the blisters were all gone and my feet felt tired, but fine. Still don’t know how that worked.
I have that concert shirt, so I remember the time frame. That was 1996 that they toured with Zak and did Quadrophenia in its entirety.
Black Flag, The Meat Puppets, The Nig Heist - Perkins Palace, Pasadena (1983)
It had all the elements… I was young, on a crazy road trip, Jello Biafra and John Doe were at the show (and I met them), the bands were great and the crowd was totally out of hand. Apparently there is a film of the evening, but I have never seen it.
A few others I have seen multiple times and they have never disappointed…
Nomeansno
Carolyn Mark
The Young Fresh Fellows
The Minutemen / firehose / Mike Watt
The Sadies
Frank Zappa back around '85.
Genesis, *Abacab *tour in '82, when they played all of “Supper’s Ready”.
Every **Richard Thompson **show I’ve ever seen.
- Peter, Paul, and Mary.
Carter-Barron Ampitheater outside of Washington DC. Got there early. Didn’t want to hear anyone except them.
Guy comes out and opens for them. Dude in shirt and jeans. Couple of guitars, one a 12-string. Curly hair. When the announcer said he was gonna play his “Canadian Railroad Trilogy” a few people clapped, but I never heard of him. Gordon Lightfoot. He was pretty good.
PP&M were great, and late in the concert they brought out this guy who wrote a few of their songs to sing with them. Short guy. Nerd. John Denver. Leaving on a Jet Plane. Never heard of him.
NOW it seems like a big deal to me. 
The Who, Chicago, 1979. The Who managed to make Chicago’s International Amphitheatre, acoustically a truly awful venue, sound phenomenal. And they also did an unexpected third set, so apparently this is a tradition.
FYI, this show was two weeks after that stampede in Cincinatti where 11 kids were killed at a Who concert. Everyone was extremely subdued, polite, and orderly at the concert. I recall towards the end, I was in my seat and I felt a huge hand descend on my shoulder… I look around, and see the biggest, baddest, scariest biker-looking dude looking at me (I was a skinny 17-year-old at the time). “You dropped you’re coat, dude,” and hands it to me. erm, uh, thanks! eep!
I have seen a lot of concerts over the many years, in a variety of venues and I think some of the best were up and coming or past their peak big names playing in bars or at festivals etc. I much prefer intimacy and proximity to the artists over big extravaganzas at arenas or big outdoor venues like Alpine Valley.
Some of my fondest memories, in no particular order:
Robin Trower in a bar, mid eighties.
Blue Oyster Cult, before anyone around here had heard of them (1974 or so) at the National Guard Armory.
Stevie Ray Vaughn at a smallish outdoor venue, just as he was becoming known.
Storyville, bar with fantastic sound system.
Brian Setzer Orchestra, same bar.
Ian Moore, same bar
Emerson Lake and Palmer, at their peak, arena but …WOW.
Ronnie Earl and John Mayall’s Bluesbreakers (Coco Montoya on guitar) outdoor blues festival.
Alice Cooper Billion Dollar Babies tour. I was fifteen and really into that!
What a small world… I was at that concert too! The one where he came out for the encore in his bathrobe and said “Let’s wake up the neighbors!”
Pink Floyd Boston Arena (or Music Hall; the details are fuzzy), Fall 1973. They had just put out Meddle. I went with a friend. I said they wouldn’t play “One of These Days.” He said they wouldn’t play “Atom Heart Mother” (because of their complexity). They played both. They perforned a total of 9 songs (including the encore) in a 2 1/2 hour concert. In addition, they did “Echoes,” and a truly brilliant version of “Careful With that Axe, Eugene.” At one point, they all left the stage for ten minutes while playing a tape of concrete musics (footsteps and such) and it was fascinating. For the encore, they surprised everyone with a really first-class blues jam number – great music, but since it wasn’t typical Floyd, it was perfect to keep there from being a second encore.
Other choices:
Bruce Springsteen, Union College Memorial Chapel, Fall 1974
Rock and Roll 9 – a minifestival held at the Hollywood Speedway in Florida in December of 1972(?). Among the acts were Jo Jo Gunne, Elvin Bishop (who was great), Mahavishnu Orchestra (much better outdoors than indoors, since they crank everything to most people’s pain threshold), Allman Brothers, Edgar Winter (with special unannounced appearence by his brother Johnny, who had given up touring at the time), John Hammond, and Roxy Music
In chronological order:
Metallica, early 1989 at Reunion Arena in Dallas on the “Justice for All” tour. I saw them five times between '87 and '92, and that was the most intense show I ever witnessed.
Cracker, October 1992, with like 25 people at a club in Deep Ellum. They played like it was packed to the rafters.
Pink Floyd, front row center at Texas Stadium, spring 1994. There’s nothing quite like “Astronomy Domine,” a not entirely legal state of mind, a few million watts of animation and lasers, and 50,000 cheering people directly behind you. When the thunderstorm started in the middle of “Run Like Hell,” it just felt like part of the show.
James Cotton with Jimmie Vaughan and the Tilt o’ Whirl band, January 2001 at Antone’s in Austin. The world’s best blues guitarist welcomed Muddy Waters’ harmonica player to his new home in Austin. Amazing show, plus I met my wife.
A couple of oddly different shows and out for me. I saw Nirvana on their *In Utero * tour in Davenport, IA. The entire floor was packed with moshing teenagers. For safety sake (and sanity’s) the wife and I spent most of the show in the balcony. Nirvana were awesome.
I had a totally diffent experience when I saw Sugar on the first night of their *File Under Easy Listening * tour. It was in Decorah, IA and there was hadly anyone there. By the end of the show, it was almost vanant. We spent most of the show sitting in the bleachers, as had become practice in our old age. By the end of the show though, we could just walk up and stand right in front of the stage. In true Bob Mould fashion, they were louder than shit. It was so nice though to be able to take in one of my favorite musicians from up close without having to worry about getting kicked in the head by a drunk 14 year old.
Since there’s been a couple people mention concerts other than the rock and roll variety, I’ll throw this one out. Lew Tabackin at the Artist’s Quarter in St. Paul, MN. That guy has some lungs. Doesn’t even need to play into a mic to fill the club with his sound.
With a jealous nod to those of you who saw The Great Bands in their day (which was, unfortunately, before mine):
Bobby McFerrin in 1987? Before he became famous. Smallish theatre, excellent seats. He came out on stage barefoot, no opening act, no instrumentalists. Just him. A couple of people giggled as he began his a capella performance, thumping on his chest to keep rhythm. By the end we were all with him. When we left I floated back to our car, my feet never touched the ground.
Corky Siegel (2003) toured with the orchestra I played in as we traveled to England. It was a homecoming for our orchestra’s conductor, so the energy was particularly high. Corky is a master. Scrawny and electric. He drew them in, pushed them out, yanked 'em forward and had 'em sit back and think about it for a while. Afterwards there was a reception and I remarked to some locals that when Brother Corky comes to town to give you the Word, you best listen up.
Various Unnamed Pimply-Faced Teenagers (1985) My sister attended the University of Cincinnati’s College Conservatory of Music each summer while still in high school, so of course we went to the concerts. All of the students were good, but I’ll never forget this particular group of jazz musicians, playing brass instruments.
They shambled onto the stage the way teenagers do, looking all feet and elbows. Bad haircuts. Posture that makes every mother cringe. Really it appeared that they might be called away to salt some fries for the drive-thru any moment. They put those instruments to their mouths and KEBLAMMM! The music that came out of those kids took my breath away & tears just rolled. No idea what pieces they played or who they were, but I can still picture them. Those kids made music.
I saw Midnight Oil at some theater-type venue in Houston (can’t remember the name) in 1988. I like the Oils, but live, thay were absolutely phenomenal. They veered from hardcore-hard to airy folk and back; the dynamics were amazing. Jim Moginie and Martin Rotsey are an incredible guitar tandem. Rob Hirst was a unique and intense drummer; more of a front-line than a back-line guy.
Kiss Destroyer tour in 1976 at Barton Colisseum, Little Rock. I was only 13. Kiss was my favorite group at the time. Not that it was an especially great show, but I was there, then at that age.
Soul Asylum was a great live band, too. I saw them at The Nick in Birmingham in 1986 (maybe 1987). I played pool with Dan Murphy before the show.