I'd stay away from the Bahamas like the plague. I'm not a fan of those islands, even the Atlantis doesn't do it for me. There are several all-inclusives located nthe Caribbean that will be good for your group. Beaches in Turks and Caicos is a good choice, as well as a few located on Barbados. I'd stay away from Jamaica, even on an all-inclusive resort for safety reasons. There are also some located on St. Lucia, but I have no personal expereince with them. My favorite way to vacation to the Caribbean is we rent a private villa on St. John. We (only a family of 4) usually get a 3 or 4 bedroom home with a private pool, and it's the BEST!!! St. John has some of the best beaches in the world, and staying in a private villa is just so relaxing. You can eat breakfasts in, and slowly meander your way around the island. We don't cook, except for the brakfasts, but sometimes we've grilled some steaks for dinner. Also, with the location of St. John, you can take either a charter boat (think excursion here) or a ferry over to the BVI's which are also beautiful. St. Thomas is only a ferry ride away(You fly into St. Thomas) for WONDERFUL shopping. If you want any further information about renting a villa, let me know.
Edited to add: I've been to SEVERAL of the Caribbean Islands (All of the USVI's, BVI's, Antigua, Bahamas and Bermuda (though neither in the Carribean), Barbados and the Caymans) and St. John is truly paradise!!!!