I’d like to ride down the chocolate river in the Magical Mystery boat in the original Willy Wonka.
Okay, just because of that, I want to be the pizza delivery guy.
We’ll never forget you!!
I’d want to be the girl in the tango scene from Scent Of A Woman, obviously.
Since mine won’t… I’ll go with the very first thing that sprang to mind reading the OP: a certain scene from *The Thomas Crown Affair * (1999) with a certain Rene Russo, and a most singular dress. 
I was thinking the glider scene from that film. Looks fun.
Along the same lines as the Rene Russo/Thomas Crown Affair comment, I’d like to be Billy Bob Thornton’s character in the famous sex scene with Halle Berry’s character in “Monster’s Ball”, but that’s just me. 
I, for one, would LOVE to ride around the forest on the (shoulders? Branches?) of an Ent, like Merry and Pippen did in LOTR.
Well, there was this movie I saw once, I’m not sure if I remember the title precisely. I think it was something like Ball Draining Cum Sluts Vol. 17? I’m sure our more knowledgeable movie buffs will correct me.
I’ll take any scene in that one.
Either Contact, when Ellie goes for a ride inside the Machine, or The Quiet Man, when Sean finds Mary Kate at his house and kisses her properly. 
Dirk Diggler making his onscreen debut with Amber Waves.
Either the last scene in It’s A Wonderful Life, or the last scene in The Princess Bride.
Tony Curtis on the yacht with Marilyn Monroe in Some Like It Hot
I’d be Marcus with Alex draped naked across me for a good, long, post-coital nap toward the end of Irreversible. Mmmm…buck naked Monica Bellucci.
That or Tony Stark blasting around in the suit, mocking jets as they try to get him to identify himself.
Either:
-the scene in the Black Swan. Any of the characters, really.
-Avatar when he’s on that big dragon. Hell, when he’s with any dragon. I want a dragon.
Riding on Falcor, this is the only granted movie wish that successfully read my mind.
The scene I have in mind features the song “Moving In Stereo” and Phoebe Cates.
**I want to hack people up with a machete like Jason Voorhees! **
Oh I mean some scene where I get to kiss a pretty girl.
Before or after hacking her up with a machete?
I’d be Miho from Sin City, being all badass with a sword.