I could definitely see Gene Wilder as the 4th Doctor. I'd love to see Christopher Walken as a Doctor (though I have no idea of some of the movies that were shown in which he appeared.)
I love Galaxy Quest! Sam Rockwell aka Guy Fleegman (Red Shirt) and Tony Shalhoub as Fred Kwan were the best (as was Alan Rickman...heck, everyone in it played their roles well!)
Monk as a Doctor? That would be interesting, considering his idiosyncrasies. Mr. Shalhoub is a very versatile actor, though. Liked him in MIB and Thir13en Ghosts.
Paul Muad'Dib always looked rather like a wax figure to me, but then Chris Walken kinda does, too. Guess it's the very taut skin or something. And I could see Bryan Cranston as the 12th.
Who would you choose as The Doctor's previous (or next) regenerations?