I agree with Epcot. Anytime we arrive and only have a partial day at a park, we get our 3 FP's at EPCOT, use those and head back to WS for the rest of the day and finish the day with Illuminations.
We normally go for 7 days and allow 2 full days for MK, one of them being our last full so we leave our trip with all the magical memories. We allow 1 day each for HS & AK, another day for Epcot then PH to a late night park or enjoy swimming a the resort, mini golf or DTD. We normally split the other day between any of the other parks that the kids want to spend them at (PH if needed) and then our last day we rope drop to one park that the kids mutually agree to for one last ride on their favorite ride then head to DTD for lunch, Goofy's and EoS for sandwiches to go to enjoy at the airport while waiting on our plane home.