We go there 4 times a year, so here it goes. I stay at the Marriott cuz I am a points kind of guy. But if you ask nice, they will give you a room by the pool and the beach at the hotel is excellent. Drinks are way expensive, so bring your own and chill on the beach with a Cuban if that is your thing.
If you have a bunch of money to burn, you can rent a powerboat of different sizes from a couple of places on the island. I think I paid $500 for the day for a 26 footer with skis and tubes. You can go to Stingray City all you want and the gas is included.
Jetskis and parasailing ain't cheap, but fun to do. The hotel will help you with that for free.
If you snorkel, I highly recommend either driving yourself or catching one of the many white semi private buses that run up and down the main road to Hammerheads Bar and Grill. Each way is only 1 or 2 Carib dollars.
Anyway there is a freighter that broke apart during a hurricane that is only 200 yards off shore in about 20 ft of water that is cool to dive. We are never there long enough to scuba, so snorkeling it is. There are many large Tarpins that hang around the wreck and the diving platform that is just off the back deck of hammerheads.
If you are there long enough to scuba, there are many places close to shore or you can pay the big bucks for a guide.
There are many good places to eat, just look on Trip Advisors. Great place but can be pricey. Enjoy!