I've yet to find an airport that I would actually like to spend time in! Kai Tak used to have a good pub hidden away in a corner. London City has a good restaurant. Narita has a lot of free internet terminals and massage chairs that overlook the runways. Incheon has good food. Most other airports are pretty sucky- JFK and Heathrow are way down the list (big, inconvenient and crappy shops).