I missed out on the original incarnation, but I saw The Monkees 1986 tour (without Mike). Screaming-wise, it was the loudest crowd I’ve ever experienced.
Also saw the Davy-less Monkees a couple of times in 2012, Mike solo at the Great American Music Hall in 2013 and Micky at the Del Mar Fair in 2019.
When my wife and I were dating, she could get tix to the Baltimore Symphony Orchestra. We saw, in concert:
Paul Anka (lame show; his hits are bad)
Shirley Jones (walked out at half time)
Harry Belafonte (sounded good, looked good)
PS to @Wendell_Wagner - this was at the Varsity Theater!
Ah, so not an “only” for this thread!
OK now I am jealous.
I have seen Ween many times, they are big in the Jam band scene. I have seen Gene Ween (and band) solo on New Years eve at a dive bar in Chicago. No stage just a two foot riser along the wall between the bar and the front door. I saw him a second time there also. The the bar owner got Dean Ween to do a couple of shows (not NYE) also. These shows were kinda word of mouth through the Ween message board. Moistboyz, another Dean Ween side project, also played this bar.
I have seen Hawkwind several times, the largest venue being Cabaret Metro to the tiny Club Dreamerz. Also have seen Nik Turner (former Hawkwind saxophone player), at a festival and a suburban bar that almost exclusively books tribute bands with Mercury Rev on guitar.
No one has said Motörhead yet so I will.
A few others I’ve seen that no one has mentioned:
The Bodeans
The Radiators
Stanley Jordan
I saw Phantom, Rocker and Slick at the Vic Theatre with cabaret seating. My first concert going experiences was with very big venues, this was the closest I had ever been to the band. Even more mind blowing to me, was that all the string players changed instruments every song including a fourth man rhythm guitarist. Lee Rocker switched between bass guitars and upright basses. Songs sounded exactly like the album because every instrument was tuned for that song.
Alas, my hearing loss can be traced directly to attending a Motörhead concert, in a gymnasium, in 1985. 
Hmm, I saw Havana 3AM, Paul Simonon’s post-Clash band with guitarist Gary Myrick. Nothing to write home about, though.
How about the Corea/Clark/DiMeola/White lineup of Return To Forever? One concert where I actually ripped off a scalper rather than the other way around.
I’m guessing I’m the only Doper who has seen The Dead Milkmen live.
I’ve seen Motorhead and the Bodeans.
I’ve seen the Dead Milkmen with Butthole Surfers and The Cramps.
I know a good part of my hearing loss was because of two nights at Medusa’s hosting the Rollins Band. Of course us camping out in front of the amplifiers didn’t help. Slamming in the pit substituted acoustic pain for physical. Good times.
Not only was I wrong, but I would have loved to been at that concert!
Re: Harry Chapin…
In the 1970s, performers of the more folk/acoustic variety, who were commercial enough to get played on Top 40 radio and hip enough to get played on Album Rock stations, often played the college circuit. I saw Harry Chapin, Bonnie Raitt and Gordon Lightfoot at the same local college in Pennsylvania and Lightfoot a second time at Southern Illinois University. They all did great shows and treated their audiences well, even if they were playing a small college.
The students who were assigned to shepherd Harry Chapin around town said he was rather obnoxious, and expected them to procure drugs and pliable women for his entertainment. I remember that after the show he signed autographs, and seriously flirted with my wife’s sister, much to the annoyance of her husband.
I saw BB live. I didn’t want to go, just got off work, didn’t think I’d like it, blah, blah. But the boy I was dating insisted. So glad he did. Def one of the best concerts I’ve seen!
And…Rockin’ Ronnie Hawkins, El Macombo Toronto.
Stomping’ Tom Connors.
I saw the Beastie Boys when they were a punk band in 1983. They weren’t yet famous and I didn’t know who they were. It was the first show (not a “concert”, though) I was ever at and they were opening for the band I went to see: The Dead Kennedys.
I saw Guns and Roses, Deep Purple and Aerosmith all on the same night. One of the best shows I attended. General admission at Giants Stadium and I was pretty close to the stage.
I saw G’n’R with Faith No More and Soundgarden opening in 1992. The opening bands were much better.