Last time I was in Jamaica, I noticed a HUGE difference between the marine parks (and other preserved areas) versus the regular ocean. The regular areas were in terrible shape, almost devoid of life. The protected areas (where the dive shops tend to take peope), on the other hand, were far, far more impressive. So keep that in mind, if the divemaster decides to try somewhere radically new, or wants to go drift diving.
On the bright side, the visibility was amazing. I was eighty feet down at one point, and it was as clear as glass - you could make out every detail on the boat hull above us. And in the protected areas, you can have the whole "Jacque Cousteau" experience - schools of fish swimming above, rays digging into the sand . . . lot of purple sea fans, too. More than enough sea urchins, too
Beyond scuba diving, if you've never been to Jamaica, both the biobay at Falmouth ("Luminous Lagoon") and Dunn's River Falls are worth visiting. Walking up the falls, though, is a bit athletic (but fun). Oh, and everything is deserted on Sunday mornings, so its a great time to get personal attention and avoid crowds.