Hi Stacey!
Welcome to the Disney Parks Moms Panel. I'm glad to tell you that other than seeing a lot of tutus and glitter, I don't think
Disney Princess Half Marathon Weekend will have an impact on your trip!
Saturday, February 25th is the Disney Enchanted 10K and Sunday, February 26th, is the Disney Princess Half Marathon. The 10K will begin and end near
Epcot, likely before that park opens for the day. For the Half Marathon distance the official course has not been released yet, but traditionally the halfway point is through Cinderella Castle and the last mile is in Future World inside of Epcot.
Magic Kingdom should be unaffected by the race, but you might see slightly heavier traffic entering Epcot as the park will open before the race concludes.
When I've ran this race in the past, I feel like most runners will head to Magic Kingdom or remain at Epcot, but the crowds themselves will be relatively unaffected. I hope you have a magical trip and please let me know if you have any more questions!
-Lindsey