If you are set on Sandals, try Grenada. We ave been looking into that in the background but other trips have come up. You can dive with Sandals but the diving structure is not that great IMO - dives site choice, short dives, regimen, etc. Quite a few posts on Sandals diving in general and some by me. We generally go with an offsite dive op but the cost is more. The Sandals properties will be nice. These comments are apart from the Beaches chain as they allow children.
Royal Bahamanian in Nassau is ok but the resort is tighly packed onto the property and I personally am not a fan of the diving in that area. YMMV. Good beach though but there can be alot of people. Access by bus (easy) to alot of activities in/around the city.
St. Lucia has decent but not spectacular diving and 3 resorts. We only stayed on La Toc which has become huge. Too big I think. La Toc doesn't have much of a beach but does have large pool decks and many pools.
Royal Bahamanian in Nassau is ok but the resort is tighly packed onto the property and I personally am not a fan of the diving in that area. YMMV. Good beach though but there can be alot of people. Access by bus (easy) to alot of activities in/around the city.
St. Lucia has decent but not spectacular diving and 3 resorts. We only stayed on La Toc which has become huge. Too big I think. La Toc doesn't have much of a beach but does have large pool decks and many pools.