We were at YC over FW marathon weekend. The resort itself wasn't impacted notably to my eye, but there ARE inconveniences wrt getting around the mornings of any race, so I would recommend doing parks you can walk/boat to those days. Also, going to Epcot the Monday after the race was INSANE at the IG entrance, though the park impact from a different marathon might be different. I was in line 30 min before early entry and missed all but 5 min of early entry.