We used the plan last summer, DH, DD and a friend, and me, and it paid for itself in a couple of days. The girls were both 16, and they loved the water mice. We all did! We were there for ten days and didn't use the mice on only one day. It was great.
I thought you had to be staying at the hotel where you sign up for the plan, that you couldn't, say, stay at the Boardwalk and sign up at VWL. And I'm pretty sure the family plan is offered at the Contemporary.....
Kids have to be at least 12 years old, five feet tall....