I ran my first Disney Marathon in 2007. I really enjoyed the race, but my performance was a little disappointing.
We combined a family vacation with the marathon. To accomodate the kids' school schedules, we toured the parks during the week prior to the race. I stayed off my feet on the Saturday before the race (except for packet pick-up), but that was not enough to recover from five long, fun-filled days in the parks. I knew within the first 3-4 miles that my feet and legs were going to be sore the whole race, so I made my peace with the idea that I was going to be slow. From that point, I kind of freed myself to take it all in.
I loved running in the parks and wish there was a way to incorporate more of the miles inside them. When we ran into the Magic Kingdom and onto Main Street through a backstage area near Space Mountain, U2's "City of Blinding Lights" was being pumped through the surrounding speakers. U2 is my favorite band of all time (minus most of the 90's - I'll forgive them for Zooropa and Pop), and that song is one of my favorites. Every time I listen to that song, I think of running on Main Street.
It was unseasonably hot, and the out and back stretch between DAK and DHS was particularly brutal. Once we got into DHS, I thought the route was great, even though we had some concrete to deal with on the path between DHS and Epcot.
Hopefully I'll get back for the marathon with the next couple of years. We're planning on the Wine and Dine 1/2 in October, which ought to be a lot of fun.