Hi Terry!
I think you've got a great plan to tour the Parks with just your wife while your four year old has some fun of their own.
Walt Disney World has got you covered with nightly
Children's Activity Centers and In Room Child Care options! There are fabulously themed Children's Activity Centers located at the following select Resorts:
Disney's Animal Kingdom Lodge ~ Simba's Club House
Disney's Polynesian Resort ~ Never Land Club
Disney's Wilderness Lodge ~ Cub's Den
Disney's Beach Club Resort ~ Sandcastle Club
Walt Disney World Dolphin ~ Camp Dolphin
Hours vary based on location. Advance reservations are recommended for all locations, except at Camp Dolphin where they are required. Reservations can be made up to 180 days prior to your arrival to the Resort by calling (407) WDW-DINE, or (407) 939-3463. I have to tell you that when my children attended the Never Land Club, they didn't want to leave! They enjoyed themselves so much that they begged to go back the following evening! We also used the Sandcastle Club on our next vacation and the kids enjoyed that just as much! Kids must be 3 to 12 years of age (4 to 12 years of age at Camp Dolphin) and fully potty-trained. In fact, my eleven year old daughter has recently pointed out to me that we'll need to let her go to the others before she reaches the maximum age of twelve!
Please come back and see us if you have any other questions we can help with!
Wishing you Pixie Dusted vacation planning!
~Jackie