My wife and I have been to Sandals resorts in Jamaica five times (Montego Bay 3x, Negril 1x, and White House 1x). We enjoyed them all and there are a reasonable amount of available activities within the resorts. We have not seriously priced it out for a return trip in the past few years, but when we last looked pricing had gone up substantially. In the past, we thought it was fairly priced.
While there are some things worth seeing outside the resorts, I'd say Jamaica is not the best place for exploring without a substantial group.