I agree with the pp. The parties are getting more popular year after year and it's hard to tell when one will be busier than another. We have been to 3 Halloween parties and 2 Christmas parties (with 1 of the Halloween parties being on Halloween night), and we didn't find any of them overly crowded at all. But with that said, everyone has a different perception as to what's crowded and what's not; so what might be horrible to one, might not necessarily be bad to another. If I was looking to go on a not-so-crowded night, I would probably choose a week day as the weekend parties probably have a larger attendance since you have the locals that might choose one of those over a week night, which adds to the vacation crowds. But I think you'll have a great time, busy or not, as the MK is so festive all decorated for fall/Halloween and it's fun to trick or treat in the park....plus the parades are great.