We were there mid June 2002 and stayed over until Monday, thinking the same thing. Boy were we wrong. It was the absolute worst couple of hours I have ever spent at the MK. It was packed, perhaps with people who had just arrived that weekend? And because it was so late and so crowded, there were no fastpasses left for anything. It also poured rain, but that could happen any night. All we were able to do was Peter Pan after about a 45 minute wait. After we waited about that long for Buzz, they announced that it was broken down and we all had to leave. Thank goodness we had spent 9 great days at the parks and had already ridden everything. We were just trying to go back to some favorites.
Just telling you this tale of woe so you won't expect the park to be deserted. First thing in the morning and the second half of e-night are both a million times better.