I've run the marathon the last 5 years and I've always thought, even with the race weekend, the crowds were pretty low. The half marathon is on Saturday and will most likely be over by 10:00AM, and the course only runs through MK and Epcot. The full marathon is on Sunday and goes through all 4 parks, starting with Epcot, MK, AK, MGM and back to Epcot. Probably cleared out of Epcot by 2PM. It's a 6AM start both days, so you probably won't be too bothered by the runners, although they will have the course roped off and you'll need to wait to cross the course til there's a break in the runners - a CM usually assists in this. Finally, most of us go to the parks the day after our race, but as we've just finished 13.1, 26.2 or 39.3 miles, we'll be limping along so slowly, you can easily outrun us to the attractions. We'll be wearing our medals, so be sure to congratulate us as you whiz past us!