Asahikawa has only business hotels. The Washington Hotel in front of the station is convenient.In Otaru, the Grand Park Otaru (formerly Hilton) is most popular.
In Furano I recommend a pension:
http://www.furano-kankou.com/english/hyperlinks/accommo...
In Noboribetsu, the Takimotokan has the longest history and nicest baths:
http://www.takimotokan.co.jp/english/index.html
In Hakodate, I think there are only business hotels around the station with the ANA Hotel among the more comfortable. If you like hot springs, you might prefer the Yunogawa area at the city outskirts.