We usually have a 3:00 DME pick up. So we go for a special leaving day breakfast, then nip into closest park for a couple of hours.
If you don't want to add on a day to your tickets, you can resort hop on the monorail. Walk over to MK and hop on the boat to Poly, walk around the resort, enjoy lobby, gift shops, grounds, get a Dole Whip! Then walk along the lake to GF to explore. Love their gift shops and beautiful resort grounds. Sitting in the lobby is a treat in itself.
Get monorail back to CR.
Or take the boat at the CR marina to Ft Wilderness and explore their shops, I love walking around the Circle D ranch just a little way past HoopDeDoo buildings. You can take walking path or boat to Wilderness Lodge, then take the boat back to CR.