Castle Club is on the third floor and has it's own reception and lounge where you have breakfast, and can indulge yourself with afternoon tea and soft refreshments. It also has an exclusive lift down to the park and every guest in the party will get a VIP fastpass.
As far as I know there aren't any family rooms in Castle Club, only standard rooms (sleeping 4 plus an infant) and suites. Have you booked a family room for the extra space or because of the size of your party?