As your research may have found out, there are no major hotel chains here. The biggest hotels here are the Fairmonts (the Southampton and the Hamilton), but I'm not familiar with their rewards program. I believe that the Wyndham is still closed (due to damage from Hurricane Fabian).

I'm not sure of your travel budget, but one possible strategy may be to wait for a special vacation package. The goverment did a promotion a while back ago to increase turism where they subsidized some airfare and hotel costs for selected vacation packages. This may lower your costs to a more acceptable level. From what I understand, it was a fairly successful promotion. So, chances are that it will be repeated. (However, no guarantees either express or implied are given that the promotion will be repeated... <G>).

For what is worth, when my sister came to visit, she and her husband loved the island.