Another optoin for long layovers at ICN...go to the Korean Spa. "Spa at Home" is in the basement of both Terminals 1 and 2. You have to clear immigration and "enter" the Republic of Korea, go through baggage claim, and exit down the escalator. But the spas are nice, are inexpensive, and have "nap rooms". If you haven't experienced a Korean spa I highly recommend. Note however that traditional Korean spa rules apply. When using the hot tubs, showers, and steam room you MUST be naked. (cue the gasps from the Americans.) Note the nude areas are gender separated. (Korea is not Germany. )