We've stayed at the Marriotts in Curacao and St. Kitts, both of which we liked. I would go back to either, but our problem is the lack of direct flights. I hate wasting time on connecting flights on vacation...
I would also consider the JW Marriott or CasaMagna Marriott in Cancun (they are next door to each other.) We stayed at the CasaMagna and were very happy with our stay - we got an upgrade to oceanfront, top floor. We split time between the beach and pool, had a rate with breakfast included. All in all, it was a really great week. And don't be put off by Cancun being labeled a party destination, the two Marriotts are in a nice, quiet area.