We rented DVC points (Dinsey Vacation Club -- Disney's version of a time share but rather than buying a certain week, you buy points which can be used whenever you want to go) from a fellow DISer and stayed at the Villas at the Wilderness Lodge this past spring. We had our then "just turned 2" year old and our "about to turn 4 year old" (they are 21 months apart) with us. We rented a studio and it was fine for us but I think if we had a baby with us as well I'd try for a 1 bedroom. We rolled our side by side double stroller right onto the boat everytime we went to the MK. Our kids are big monorail fans and also really liked the boat so to get to Epcot we took the boat to the Contemporary and then the monorail. No folding the stroller then. There is no resort that you can either boat, monorail or walk to ALL the parks. You'll have to take a bus to at least one park from all of them. The only way you can only need a bus to one is to stay in the Epcot area (Beach/Yacht Club, Boardwalk, Swan or Dolphin). At those resorts you can take a short walk or a boat to Epcot, a longer walk or a boat to MGM, a bus to the Animal Kingdom and to get to the Magic Kingdom you have to walk all the way through Epcot (you'll enter through the "back door" in World Showcase then have to walk all the way around and through Future World) to get to the monorail, take the monorail to the TTC, change monorails and go to the MK. Plan for this to take a minimum of 45 minutes and there is no way to do this and be there for park opening or to do this at park closing.
My opinon would be that one of the MK area resorts would be most convenient b/c of easy access to the MK without having to fold up the stroller and easy access with one change of monorail to Epcot. The exception is the Poly where you can walk to the TTC and take a direct monorail to Epcot. Resorts with busses to all parks would be all of the values, all of the moderates, AKL, Old Key West and Sarasota Springs.