Been to many places...would vote Kauai number one (though I'm biased to parts of Italy being 100% Pisan). Stayed at the Westin in Princeville prior to it being severely damaged by Hurricane Iniki...several years later we went back and stayed at the Grand Hyatt in Popui Beach. The island is truly majestic in all its splendor.
Bermuda is gorgeous as well, stayed at the Southhampton Princess and Castle Harbour. Cool thing about that island is biking all around on mopeds. And, no matter where your adventures take you, there is no poverty, unlike many other places once leaving the resort area.
Loved the Dominican Republic...stayed at Casa de Campo...the resort is incredible and extremely vast...which is a good thing so you never have to leave the grounds.
The El Conquistador in Puerto Rico is very nice and Old San Juan is neat...and just when you think you're no where near a basketball court...you stumble across one named after some SU icon.
Out of all the Virgin Islands we've been too...liked the serenity of St. John.