Riverside is lovely, but those rooms are small. We just returned from a great week with Mickey and we spent a night at Riverside before joining my parents in a larger room at Old Key West. We were tired from the long drive and enjoyed the pool, then had a nice meal at the food court. The grounds are beautiful! But back in the room I was climbing the walls because the kids were manic and there was nowhere to hide! We had a room with the trundle bed and when that is pulled out for sleeping it's very tight -- little space for suitcases, etc. And we didn't completely unpack because we were only staying one night.
Now -- Ft. WIlderness. Magical, green, peaceful and fun. A little world all its own. Buses run within they campground and then a bus or a boat takes you to the parks. There are little playgrounds for the kids, 2 pools, petting zoo, a great buffet restaurant -- I LOVE this place. There are codes at Mousesavers. com right now for $169 for the cabins -- GO FOR IT! There is a full kitchen and bath, a small living area, and a separate bedroom wiht bunk beds and a full bed -- much more room for 5. You can have breakfast on the deck! We stayed last Spring with my parents (4 adults 2 kids) and we loved it. I could literally visit Ft. Wilderness and never leave the whole week!
Have fun!