[Shaun]

Hmm. Well noone will touch my favourites because they're too impossible to sing (While My Guitar Gently Weeps) or too unknown by the masses (In My Life).

Some I'd be interested in seeing:

Paije - I Want To Hold Your Hand (quite probable given his past performances)
Rebecca - Oh! Darling (recently covered by Florence + the Machine, would like to see her or Katie try it)
Cher - if she DARES bring in some rap I'll throttle her. I guess 'Come Together' would provide her with a platform to gurn and move stupidly, à la Olly Murs.
Katie - see Rebecca, or Let It Be
Matt - Something would be quite nice from him. Not much in the way of falsettos for him.
One Direction - I'd rather they died. But I imagine they'll get something like She Loves You.
Mary - hmm. Blackbird? That'd be interesting.
Wagner - lmao. err. Back in the USSR? Ob-La-Di, Ob-La-Da? I Am The Walrus? omfg I hope it's the latter. COO COO CA CHOO.