We have friends in Disney this week. It's their first trip and they asked us the same question. Our answer was pretty much the same as above - MK 2 days, Epcot, then MGM. AK only 1, maybe not even a full day.
The main point we tried to stress was that they should get Park Hoppers in order to make the most of their time there. They decided no on the Park Hoppers. The end of their second day there they called to say they wished they had Park Hoppers. They need more time in Epcot and MGM, not a full day probably 1/2 day each, but their tickets are only good in one park each day.
If you can afford Park Hoppers, thats the way to go.
They arrived Friday night, leave next Friday night, so time there is about the same as your trip.