Any month but summer. We stay away June, July, and August. It is too hot and the lines are too long.
Family tradition takes us there the two weeks after Thanksgiving as often as possible. No lines and beautiful decorations.
We love October for Mickey's not very Scary....
Any January because it is so leisurely.
May is good because the lines are not too long and it is still warm enough to swim everyday, but not too hot...
From - Ticofan
by the way, we are from Utah - The family has probably been 40+ times!!