We were there from Jan. 1, a Sat, through Mon., Jan. 10 in 2005. It wasn't until the third or fourth day that crowds diminished, but by Tues. the parks were as uncrowded as I've ever seen, and they pretty much stayed that way for the rest of our vacation. The only impact the marathon had on us was we were froced to walk on the grass along the boat canal to MGM that morning as the sidewalk was part of the route, and once in MGM we had to wait briefly to cross the main street for runners to go by to get from one side of the park to the other. MGM's rides and attractions had short lines.
Bill From PA