I think if you stay away from MK on Saturday, you'll be okay. If you follow the Day After theory (go to parks the day after they've had Early Entry), it would be MK Friday, AK Saturday (but I would do Epcot instead), and MGM Sunday. If you're staying onsite, you might want to also do MK Sunday morning for a few hours if you can make it to the 8 a.m. Early Entry. The Early Entry parks tend to get very crowded just before lunch time. If you only have three days to do all the parks, you might want to skip AK all together. Saturday at Epcot shouldn't be too bad. It's such a big park that people tend to spread out. Unless of course there's some special event going on. Whereever you go, GO EARLY!