Hello and welcome to the DIS!
I have read that people have coordinated birthday parties for their children in various areas of the ship - sometimes in one of the restaurants during an hour when it is closed for meals, for instance.
On the suites, there are three levels. The CAT 3s have a living room area and a separate bedroom, with 2 full baths. We've done this one and the extra space was awesome! The CAT 2s are two full bedrooms with a living area and the CAT 1s are either the Roy Disney or the Walt Disney suites - also two full bedrooms, a separate "study" and a separate living/dining area. The verandas on all of these are much larger, too. With any of the suites you get concierge service - early opportunity to make on-board reservations, a concierge meet when you board for additional reservations, a full itinerary provided of all of your daily events, and they provide you with some sort of "treat" each night - petit fours, color pages/crayons or arcade cards for kids, etc. In the CAT 1s and I think CAT 2s, you also get complimentary soda/water kept up all of the time in your stateroom. In the CAT 3 you get an initial stock.
I am sure that the concierge would gladly help you arrange a party for your son - several people in the CAT 1s have actually hosted parties in their staterooms, so that's a possibility, too.
Good luck!
We used it as the luggage storage room.
