We loved September in both 09 & 11. It was hot, around 90 when we went but the weather was great with only one rain shower that lasted maybe an hour out of 13 days total. Crowds were, what we felt, light and we waited longer for meet n greets than for rides. The MNSSHP was awesome once all the little kids went to bed and it's true that the decorations are beautiful. We have never gone in spring so I can't speak as to visits then but September is very nice.