I've been down for the past 4 years for the marathon weekend...wait times for rides are minimal. There are races on Friday, Saturday and Sunday. Friday's "Up" themed 5K begins at 7:00 am at Epcot and is finished and cleared out well before the park opening. Similarly, on Saturday, the half-marathon which starts at Epcot, goes through MK and returns begins at 6 am and everything is cleared out by 10. Sunday, the marathon spans all 4 major theme parks and traffic between parks, particularly AK and DHS is very congested until around 1:00 pm. Use monorail transportation if possible (be prepared for trains crowded with race spectators) or give yourself an extra 45 minutes (by bus) if you plan on being at any of the parks when they open on Sunday. Otherwise, crowds are fairly small and wait times rarely exceed 30 minutes for most rides. One of the biggest disappointments is that Spalsh Mountain has been closed for rehab the past 3 years. In '06 the weather was in the 30's in the morning. In '07 late morning temps got up to 89. The past 2 years were around 80.