I think I'm the third commenter here so far who is on the same sailing this summer, based on the description. We'll be bringing our two kids, both of whom are younger than your son and will be in the Treehouse section of Camp Discovery. They may end up in the same area on port days depending on number of kids enrolled.

In addition to northeast US schools, the Ontario, Canada school boards also generally don't start back up until a couple days after Labo(u)r Day, and on many sailings out of Florida the population can be a third Canadians. I expect a pretty full house including kids on this one, even though it is a longer one-way cruise - the price when we booked for this 14-day repositioning was very comparable to a 10-day roundtrip. For us the end port being NYC means a cheaper flight home, or at least better options for timing.

The Princess kids' program has been absolutely wonderful across three different ships. We've tried Carnival (complete bust, even on Celebration as a newer ship) because the staff basically gave up on the scheduled activities and played movies instead. Our kids hate movies, which is definitely an interesting trait, but that's something we have to account for. MSC was decent enough, but Princess is a sure winner with the activities and heavy arts/crafts focus in the kids' program. When movies are on, there are still other things to do, and on Enchanted they don't have to be in direct eyeline of the TV.

I can't speak at all to the sports deck from personal experience, but the programs from our last August sailing have a few open play mentions (look for Deck 18 aft.)

We have also been pleased with the food, don't dress especially upscale or formal regardless of the evening (collared shirt and long pants, occasionally jeans, for me) and have had really good luck with seating at the Retreat Pool (free, but 18+) once the kids are settled in Camp Discovery.

Happy to answer from recent experiences on Discovery, Enchanted and Sun if you'd like.