There is a public viewing area at FUK's domestic terminal (not sure if Int'l has one). Its not airside, so you can take the metro to the airport and spend a few hours there even if you are not flying out (exactly what I did). There is an open area, as well as a enclosed air-conditioned/heated area. It has vending machines for food and drink as well as some view finders.

It overlooks the runway, and being Japan there are always wide-bodies going and coming.