A.R.
I took my daughter when she was 3 and we were there till midnight. We have also done the Halloween party 3 times. I would have them take a nap that day then get to the park at 4 when they atart letting people in for the party. Staying late is great, though, b/c the lines for the rides are SO short if not any at all. The parade is also great and there are 2 times for it.