Been to Hawaii 19 times, to the Caribbean over 200 times.
That said, Puerto Rico is out. While the Dorado Beach area is quite similar to Hawaii, until the old Hyatt Dorado Beach there is turned into a new Ritz Carlton Reserve in two years, no decent place to stay.
Surely Grenada, St. Vincent, and Tobago are the most incredibly lush islands of all, with Jamaica a close 2nd to any of the three. However realize unike Hawaii you will find poverty on any of them so be prepared for that.
Truly the most spectacular resort in my judgement in the Caribbean is the Canouan Resort, (formerly Raffles) on Canouan Island which is part of the Grenadine Islands. As close to Paradise as anywhere on earth. Ask Bill Gates, his yacht anchors off there regularly.
Worldspan