The taste of beer.
Two Xbox games: Psychonauts and Voodoo Vince.
I still play them from time to time, and they’re still fun even when I know where everything is and what to do at any given point, but WOW I wish I could experience them for the first time again.
I think I would be utterly amazed and enthralled if, for some weird reason, I had never experienced The Beatles, and suddenly started to listen to their works.
Even today, in today’s environment, I would be fascinated and profoundly moved by the music.
Not exactly what you’re asking for, but I wish I could go back to college/university knowing what I know now. So many missed opportunities… 
Ditto. Hoo boy.
I’d re-experience the first kiss with the first love of my life. Ours was a tentative, gentle romance over several weeks, and when we finally consummated it, it was as if the stars exploded around us and the universe enveloped us in the soft palm of its beneficent hand. She said she felt the same. I have never experienced bliss like it, and suspect I never shall again.
I’d love to forget my husband so I could fall in love with him all over again.
I’ve actually imagined this, meeting him at different ages, and I’m pretty sure I fall in love with him as easily at age 5 or age 40. Hey, there’s a movie like that, but we’re not doomed to fall in love, then end up hating each other every time (though I wouldn’t mind an iteration where he puts his dishes in the dishwasher).
carlotta, have you read The Time Traveller’s Wife? It posits a scenario similar to what you imagined.
Watching the first Lunar landing, which is to me the most amazing thing mankind has ever achieved. And, as I get older it just amazes me more and more and has greater and greater emotional impact.
I’d love to experience another first listen to Dark Side of the Moon…
Walking into the Patheon for the first time.
Firefly. Oh, to hear the words, “Curse your sudden but inevitable betrayal” again for the first time.
I still remember being blown away when I saw this in the theater for the first time back in 1977. I especially liked when the trailing Star Destroyer passed overhead and you thought they were showing the back but then you realized that was just the undercarriage and there was even more. I was in the 7th grade and it was the first movie my parents let me go see that wasn’t something put out by Disney.
I also remember going to see the Empire Strikes Back and enjoying that one maybe more. But, alas, the years have taken it all away.
Years back they rereleased it in local theaters and I went to see Empires again.
I fell asleep in the middle! (I was working two jobs at the time) How time changes all.
The last hundred pages of Watership Down. I’d also like to have not seen the movie when I was four-- I wasn’t traumatized, but it did spoil the ending.
Walking out of Gare du Nord and into the streets of Paris to begin a four-month backpacking trip around Europe while in my early twenties. I’ve never felt more alive.
nothing. I’m looking forward to the first time of the next thing.
I AM A LEAF ON THE WIND …
ahem
The first season of LOST, specifically the first 4 eps (or 3 eps, if you count the 2-part pilot as one), culminating in the episode “Walkabout.”
Meanie!
+1. And I won’t be requiring the original memories back, thank you.
I’d like to see Eternal Sunshine of the Spotless Mind again without knowing the ending.
Seriously though, I’d never give up any of my memories of experiences, good or bad. They’re what make me me. As for immediately restoring or re-experiencing them - well, if I enjoyed it so much the first time, so that it’s become a baseline for the rest of my life, what kind of ripple effects would it have to re-experience them anew? How could it be any better than the first time? All I’d do is remove the context from a host of other memories, or worse, unravel them as well.
For example, what are the most treasured memories of my life? The birth of my first child… Getting an acceptance letter to my HS (which I had truly given up hope on)… Cruising down the Yangtze River and going past the Three Gorges Dam in 1997 (before its completion) and seeing sights never to be seen on this Earth again.
I couldn’t literally re-live them now, 10 to 15 to 30 years later. And to flash me back to those points in time to re-experience them anew doesn’t seem to add any value to them.
More in line with the OP’s suggestions - books or movies or games - I still don’t see how re-experiencing seeing something like The Sixth Sense or Jurassic Park again for the first time (something that truly was a different experience than watching it again) would be any better than having already seen it the first time. In fact it could only be worse, because the likelihood of somebody spoiling it for me by saying “Hey, is this the movie where the guy doesn’t realize he’s a ghost himself?” is far higher now than it was during its original first run, and that CGI special effects have advanced enough since 1993 to make Jurassic Park less of a standout than it was at the time.
Well, if this is an opportunity to re-do a singular experience that SHOULD have been good, but wasn’t what it should have been, but would be very likely improved upon if given a second chance (as opposed to simply re-experiencing it exactly, which is how I read it)…
Then I would like to start with the 2006 NLCS, Game 7, on 10/16/2006, when I was at Shea Stadium watching Jose Valentin bat with the bases loaded and one out in a 1-1 tie game at the bottom of the 6th inning - maybe 10 minutes after Endy Chavez made his astounding, leaping catch over the wall (and like Mays, throwing the ball back to double off an amazed baserunner to end the inning).
It would HAVE to end differently this time. 95 times out of 100. Right?
Can’t one of the best sports memories of my life not get ruined by one of the worst?