I created this spreadsheet to help us select a wedding date and location. We were considering Grand Cayman, Turks & Caicos, US Virgin Islands, Bahamas, Key West, Florida, Cozumel, Cabo, and a few other locations. We looked at temperatures and rainfall for a variety of locations as we wanted to avoid hot and rainy weather, as well as to find a location that was affordable for our guests who would be traveling from Detroit, Chicago and New York. It took a long time to find all this info, so I thought I'd pass it along in case it helps anyone else. It's in excel.
PS: We selected Grand Bahama. Good weather, cheap flights, nice hotels for < $300/nt. I LOVED St. John, but the only hotels on the island were too expensive (>$350/nt in low season). St. Thomas was also a consideration given the cheap flights. The problem was that the Wyndham and Marriott had some pretty negative reviews, and I hear it is very buggy.