I think it just depends on your little one. We have a little night owl on our hands. He never goes to bed before 10pm and can last much later if he's had a good nap. (He's 18 months old.) He's pretty good natured and happy - even late at night. When we were there in May (he was 12 months old then) we did the evening Extra Magic Hours at Epcot and he closed down the park at midnight - smiling and having a grand time. Of course, we slept late the next day. We are doing the Christmas party on our December trip, and I don't think he will have any problems with it. We're planning on just hanging out at the WL and relaxing that day, hitting the party that night, and sleeping late the next morning. If he does get sleepy during the party, he's generally really good about just kicking back in the stroller and going to sleep. I can't wait!