I don't usually mind long layovers if I have someone to hang out with, but knowing I'd be alone in Seoul/Incheon (ICN) for 12 hours on my way back from Thailand was making me dread my time there. That is, until I did some research and discovered that I'd hit the jackpot having my longest layover be at ICN. It's an amazing airport, and if you have to have a long layover somewhere in Asia, ICN would be an excellent pick.