Casting call

[laughingrat]

Every so often I'll hear someone say, "That movie would have been so much better if X was cast in it instead." I'll admit it, though: I'm terrible at envisioning that sort of thing (although I am pretty happy that George Raft turned down The Maltese Falcon), although it's always interesting to hear others' thoughts about it. Are there any classic films you think would have been better with a different cast?