Monday. it's the big day for MK, so that will draw on-siters who just arrived away from Epcot. Sunday's at Epcot are a destination for locals, especially during festivals.
Monday. We try an avoid the parks on the weekends as the locals are usually there. Especially if there is an event like the Flower and Garden show, Food and Wine, etc.
I'll be there next weekend too! We are doing MK at rope drop on Sunday, Epcot at rope drop Monday followed by dinner at HDDR and hopping into MK for eve emh.