Do your passes include hopping? We took our twins to WDW when they were 7 mos old, and besides MK, they enjoyed AK a lot because of all the animals to look at. My thought was that you could go to AK early in the morning and then spend the afternoon/early evening at a different park, such as MGM. Then use just MK for the other day.
When our babies were that age, we enjoyed Epcot mainly for the meals. Whenever our twins would nap in the stroller or fall asleep for the evening, we would zip over to Epcot for a nice meal while the babies slept. A nice thing about staying at the Poly is that you just roll your stroller right on and off the monorail -- you don't have to worry about waking up the baby. Staying at a monorail resort changes the WDW trip somewhat because there are endless options. It is much easier/more convenient to zip to Epcot or MK even just at night to watch a show.