The beautiful island of Jeju off the southern coast of South Korea is effectively the Korean version of Hawaii. The weather is generally nicer, there's lots of tourist attractions and plenty of leisure activities like golf. It's also just an hour's flight away from Seoul making it far more accessible to Koreans than Hawaii is to Americans.
I made Jeju a three-day vacation at the tail-end of a long business trip, and I have missed it since. I went in late November when the island was still nicer than the Korean Peninsula, but not exactly oozing tropical warmth. It's fall into the category of one of the many places I hope to make a return visit to at some point.