I agree with all of the above. If I only had one day pre cruise and I was staying on WDW property I would visit Disney Springs (formerly called Downtown Disney) for a few hours, have a meal, come back to resort to rest or swim. I would not want to deal with car seats and cabs. We love grabbing a sandwich at Earl of Sandwich. Pretty inexpensive for lunch or dinner. It is very convenient to take the bus from a resort to Disney Springs.
There is a ton to do at Disney Springs and it is just beautiful to walk around. They did a nice job of it of redoing Downtown Disney.
Another option would be to visit some of the Deluxe Resorts like AKL or Beach/Yacht Club/Boardwalk and walk around the promenade there. Or take the bus to Ticket and Transportation Center, hop the monorail and visit the monorail resorts (Grand Floridian, Poly and Contemporary). You can have a delicious Dole Whip outside at the Polynesian.
I am very much looking forward to our stay at Animal Kingdom Lodge at the end of the month. Stayed in most of the other resorts but AKL is on my bucket list!
MJ