October: Santorini Island, Greece
Greece's tourist season is long over by the time October rolls around, which makes Santorini in October a truly hidden gem.
Airfare plummets drastically to less than $550. But the sapphire seas, wineries, mild temperatures, postcard-worthy beaches and breathtakingly beautiful hotel rooms feel anything but cheap, making it U.S. News and World Report's No. 1 "Best Vacation" for the month of October.