In my opinion, instead of 2 full days at both MK & EPCOT, I would do 1 & 1/2 days at MK, 1 & 1/2 days at EPCOT, MGM & AK combined for 1 & 1/2 days, and then have a half day left over for any place you wanted to get back to. Whatever you do, however, have MK be your last half day/evening in a park.
Because of the animals, AK closes earlier than the other parks so you can easily combine a 3/4 day at AK with an evening at either EPCOT or MGM; then make the next morning the same park you finished at the night before.
It's really fun and easy to parkhop and, truthfully, you don't want to burn out at one park just so you can see everything in one day...but then again, that won't be too hard at MGM or AK (IMO, that is).
-R