Turkey seems to have become one of the best places for All inclusives.
We've been to a couple there in recent years both of which we would highly recommend. We thought we'd have a change this year and tried what, in theory, was a similar graded hotel in Zante, Greece, but the the standard was well below what we have become used to in Turkey.
The 2 Turkish ones were the Royal Dragon, near Side and Lykia World in Olu Deniz. Both had very good water parks (we have 2 teenage boys who love these), were on the beach and both had excellent food. The only downside (which seems to be par for the course with modern AIs in Turkey) is that they weren't in towns - the Royal Dragon was one of many hotels along the coast from Side (bit too far to walk) and Lykia World was out by itself a couple of miles from the town.
This year, we also went for a good water park - the Caretta Beach hotel which had a better location in that it was in a small town but the food and accommodation wasn't as good. It all depends on your priorities - if the water park is very important, it is worht looking at as that was excellent.
GreenShadow I also have two teenage boys and I looked at the Caretta beach for this year but we chose the Olympic Lagoon. It's only downside was the fact that it was about five miles from a resort (although not a very nice resort). Other than that it was great. Several pools, lots going on, good beaches and a good water park 10 minutes walk away.
Turkey is great for all inclusives, for a wide range of budgets. We stayed this year at Gural Premier Belek, which we loved. Sounds like it might suit you well as it has its own tennis centre, and also its own aqua park. Its close enough to Belek to walk into town, or get the tractor/land train, although Belek is very much a tourist town.