And what would you play?
I’d love to be in Robin Hood’s Band of Merry Men. We could play at Hide & Seek-me, Blind Man’s Bluff, Beggar-jacks & Bojinks… Oh, we’d have a grand time!
Why are you looking at me like that?
Ummm… we’re looking because you are already wearing the tights!
I would love to be in Blues Traveler… I would play the bong… er, bongos! 
I’d love to be in Kiss. I wouldn’t play anything, though; I’d just be the guy who says “You wanted the best–you got the best! The hottest band in the world…Kiss!” at the beginning of the concert. Also, I’d set off the explosives.
I’d be the guitar tuner for the Marshall Tucker Band.
Sigh. Then I’d get the chicks, finally.
** METALLICA!!! **
To take James Hetfield’s place as singer/guitar player of Metallica would fulfill pretty much every desire I’ve ever had.
Does Mannheim Steamroller count? I’ve grown to absolutly adore them in the last few years, and I’d LOVE to play in some of their songs.
Oooh…only one? I don’t have any musical talent at all because my voice rivals that of a dying crow and I couldn’t play anything remotely related to a musical instrument if my life depended on it. In my fantasy world, I would join either No Doubt, Gorillaz (as a new cartoon character too, I think it would be cool to see an animated version of myself), Barenaked Ladies, or Dave Matthews Band. And if I could play any instrument, it would be the guitar, since it’s just so cool. Or Drums.
HUSKER DU!
Man, nothing would be cooler than being Bob Mould singing ‘All This I’ve Done For You’ circa 1986.
The Chieftans. Any instrument they’d let me play would be fine, since we’re assuming that I’ll also know how to play it well enough…
I’d love to be Kittie’s new guitarist but if that didn’t work out I’d want to be David Silveria’s bitch… that counts as being in the band doesn’t it?
~Kittie
If not, you can always be my bitch. 
Oh, and I’d pick to be the lead singer of Counting Crows. But that’s just me.
My dream is to become the touring keyboardist/rhythm guitarist for Van Halen. I would quit my job in about half a second for a chance to do this.
I wouldn’t mind being in the Residents.
I could dress up like a dinosaur with a scarf and juggle peaches on stage and take pictures of the audience.
Maybe they won’t notice I have no musical talent.
Hmmm…“Superdude’s Bitch”…That has a nice ring to it
~Kittie