Sign up for Jetsetter.com (or you are already signed up if you are a member of gilt.com). From time to time they offer some very nice looking resort properties that may be what you are looking for. They had two in Belize for example earlier this week and one in St Lucia that looked fantastic and at very good prices. Sometimes they are not so cheap, so don't let the $900 a night in Fiji scare you (though that is the price for two people and it includes airfare)

If you need an invite to get in, search Flyertalk for jetsetter.com or gilt.com, there are dozens around.