Anyone who travels to Sapporo will most likely be flying into New Chitose Airport because it's actually the main international airport for Hokkaido.
Although I've used several airports nationwide, by comparison as an airport itself, I've found that I enjoyed New Chitose Airport more than I've ever guessed. It's clean, offers many amenities and is overall very beautiful.
New Chitose Airport Homepage
The New Chitose Airport, like many other airports in Japan, have a bunch of souvenirs shops, which is great for those who forget to buy souvenirs before their trip back home. The Omiyage corner of the airport is always a great choice to find those must have gifts representing Hokkaido as well.