We were there last year, the week leading up to Memorial Day. We only did the parks a couple of days. We did MK on Thursday(not terrible) before Mem. Day, and did Epcot on Saturday of Mem. Day weekend. I was really surprised at how short our waits were at Epcot. I really expected it to be much more crowded. We did Epcot and then hopped over to MGM for about 2 hours. DD8 was dying to get her chance to ride RNRC since she was finally tall enough. I think that we got lucky and someone gave us a fast pass, we then ran over to TOT and were able to ride both within about 1- 1.5 hours. I remember that area being fairly crowded , but I think it was getting around time for fantasmic, and that area always does get really congested. I think that the week before won't be too bad, you'll probably see the crowds build all week. I'm not sure about the week after Memorial Day. A lot of schools in our area, and Florida will be getting out later thanks to all the hurricanes (Ivan cost us 2 weeks of school, that have to be made up). I'm not sure how many days floridians have to make up, but I know the Pensacola area schools were out for almost 5 weeks due to Ivan. Anyway, if you have a choice, I'd pick the week before Memorial Day.
