I too have a short (16 hour) layover at ICN. I'm opting to stay in Airport Town Square, which is the area near Unseo station. I haven't been there before, but it sounds like a good option. The restaurant mentioned in this thread may be the same one mentioned in the review here:
http://www.flyertalk.com/forum/asia/...tel-queen.html
I'm staying at Hotel Sky Incheon, incidentally.