DW & I stayed for a week at an all-inclusive resort in Jamaica for our honeymoon back in 1995. It was very nice, but probably not the best value since we're not big drinkers/partiers. We stayed in Negril which had gorgeous beaches, and the sailing and scuba diving from there were a lot of fun.
Downsides to Jamaica were (then, at least) the constant warnings about personal safety. We did a couple of off-resort excursions, but at the time they made it sound like we were taking our lives into our hands by leaving the resort. Things may be different now.
Also, if going there, keep a supply of $1 bills and expect to tip people quit a bit (someone will grab your bags at the airport and carry them for you, etc.). It wasn't a big deal, but I wasn't expecting it and it was a little off-putting at first.