It depends on what you like to do. We spent a morning at Dolphins in Depth and interacted with the dolphins. Or you could try the Richard Petty Driving, or the Trail Ride at Fort Wilderness. Most of the Disney Tours do NOT allow kids, so try the Backstage Magic Tour or Keys to the Kingdom.
We did the Backstage Safari Tour at AK, it was awesome!
Golf or Tennis? Or do the Day Spa and follow up with Dinner at Victoria & Albert's. Or book the Illuminations Cruise.