I would suggest walking TO Epcot and MGM, and then at night when you're tired, take the boat back. However, keep in mind that after Illuminations and Fantasmic, those boat docks are horrendously crowded. It's great to be able to walk back to the hotel and forego the transportation lines. Also keep in mind that the boats are SLOW. But we all know how sore our feet can get from a day at the parks, so a 40 minute air-conditioned boat ride isn't the worst thing in the world.