So the Marathon weekend brings alot of people to WDW, but a large chunk of the crowds are resort/DS only. The runners need to be on transportation for several of the races by 4 AM, so most of us call it early the night before. Some runners will do parks after the races (wave if you see us walking around wearing medals) but alot of people are happy to just be walking after the full marathon on Sunday, and not everyone will be in shape to do a park. Avoid the WWoS area during the first day or two of the expo (traffic in the vicinity might be backed up a bit due to expo traffic). On race days, Thurs/Fri the 5k/10k are just in the Epcot area, and are done before the park opens. Sat with the half you may have some issues getting to the MK area (park and resorts) for early morning reservations. Some of the roads in that area become one lane, so they can only send so many vehicles in one direction before stopping, and then sending them in the other direction. Runners will be done in MK before it opens, but there may still be some runners in Epcot at park open, but it should clear out fairly soon. Sunday for the full marathon, same applies about early AM in the MK area. Even though the runners will be done in MK pre park open, it may still take them a bit to re-open the roads. AK will have runners in it for a while, DHS and Epcot will definitely have runners in them for most of the morning. I think the last runners will be going through Epcot around 1:30-1:45, exact time will vary on their speed. However most of the closures for that have minimal impact on transportation, but just watch out for runners while in park. CMs will direct you where/when to walk.
