First, the downside: Hurricane season runs through November 30. But the traditional peak in activity falls in early September, so a fall trip isn't as foolhardy as it might seem. The upside, particularly for bargain hunters, is that air-and-hotel vacation deals from a variety of providers make a trip to the no-passport-needed Caribbean islands appealingly affordable in the coming season.
Others on the list include China, Oregon, Florida, and Southern California. Hands down, for me at least, it is the US Virgin Islands (and, specifically --St John) !