New chitose airport domestic terminal has a spa. That name is Manyo-no-yu. I used it as transit passenger.
I havent seen airport which has spa. That is good idea for this airport. Maybe Hokkaido travellers are supposed to have long trip. And it includes snowboarding, sking, horse riding, touring by bike and so on. Therefore this institution is good for them.
If you have enough transit time, you should try it!