Did you know that the Flower & Garden Festival will be at Epcot in May? If you like gardens/flowers, it might be worth spending one day there, since you're so close (You could probably smell the flowers from your villa! ..lol.. )
Some other ideas--
Ft. Wilderness:
You can take the bus to MK, then a boat over there--You could rent bikes, kayaks, or canoes; go horseback riding; of course, there's the Hoop-de-Doo Review, too!
Wilderness Lodge:
The boat to FW stops there, and it's such an interesting place--They have free tours, too. Whispering Canyon Cafe is a fun place to eat, also.
GF/FW:
Rent water mice! (the ones at the Yacht Club don't go as fast, and there's a lot more to see over in the lagoon & lake) My friend & I rented these on my birthday last year from the GF, and we had a ball!!
GF:
Afternoon tea, my dears???
Whatever you do, enjoy!!