If you're there for Christmas, pull a late nighter at MK during one of their late-night EMH. Usually the first Friday after Christmas (this year will probably be the Sunday) the park will stay open till 2am or 3am for EMH. With a half hour left, the park is a ghost town. It's eery, because it's night and day (literally and figuratively). If you're there earlier in the day, you can't reach your arm out without touching someone. At 2am, you can walk around the park for 10 minutes before seeing someone. I know it's like this year-round, but it's really special during Christmas because - there's some awesome photo ops. We get close to the castle and snap some great pics, grab pics of an empty, decorated Main Street, and run around the park taking in the sites.
While the park may close at 2, they won't really kick you out - but everything will close up.