Which resort are you heading to?
My wife and I did our AOW at Sandals Grande Riviera in 2004. While the diving isn't the greatest in Jamaica, the dive staff was great (and at least we were blowing bubbles
). All of the Sandals programs have a 5 star PADI rating, and the "no pressure, no problem" attitude can make training enjoyable.
In general, I agree that it is better to finish training at home and enjoy the destination while you are on vacation, but if you are willing to do a little reading while soaking up some rays at the pool, you'll knock out the practical requirements during your normal dives so you won't miss out on much. If it's a short trip, you may want to consider just enjoying the island. If you are staying a week or more, you should be able to knock it out without feeling that it was all that you accomplished.
Sandals includes up to 2 dives per day as part of your package (differs by resort - some offer one, 2 tank morning dive while other sites offer two 1 tank morning/afternoon dives). They also offer night dives for an extra charge a couple of days a week. At least when we took the course with them, the cost of one night dive was waived if you opted for it to be one of your adventure dives in the AOW course. We always try to get in a night dive or two, so that was the part of the pitch that got us.
Good luck and have fun!