Sara:
Considering the ages of the children, it sounds like you need a dinner show everyone will enjoy!
Two come to mind: the Hoop dee Doo Revue or the Aloha Dinner at the Polynesian.
The revue is more "down-home" with all-you-each ribs and chicken and a vaudeville stage show. Get early reservations and then you can walk to Fort Wilderness's Chip 'n' Dale campfire sing-a-long to cap off the evening or enjoy the 7:15 show and get out in time to see the water pageant from the pier and maybe even the fireworks from Magic Kingdom.
The Aloha Dinner features an all-you-can-eat luau (don't miss the bread!) with a fire dancer. Held at the Polynesian, the resort is exotic just by itself! The kids will be able to join in on the hula fun!
As for the spas, there's one at the
Grand Floridian, Saratoga Springs (click
here) and one at the Dolphin Hotel (click
here) near the Boardwalk. Choose the one that's most convenient--or just consider staying at one of those hotels!
Wishing y'all a magical vacation!
Whitney