We took our two boys two summers ago and they were exactly the same age as your daughters. They had the time of their lives. We stayed at the Tradewinds Paradise Villas and even booked out trip through Tradewinds. They were awesome, and were great about taking the kids into consideration. It was a condo on the beach, and wonderful for the price. I recommend a condo with a pool. Ours loved the pool there, and met other kids their age. Plus having your own kitchen for pop and snacks is a must with two teens. (Mine eat constantly) Bring your own snorkel stuff for them. They can snorkel off the end if the piers. Many places have small artificial reefs. The reefs are nearby, but require a boat to get to. By all means take them to shark ray alley to snorkel. It's amazing. There is dancing, art, BBQ's for them to go to. They will have a marvelous time. There are numerous tours you can take them on as well. Tubing, ancient ruins, zoos. The list is endless. If they like to fish, there is all kinds of fishing. Have a wonderful family vacation.