I had a wonderful stay at Zaborin, a leisurely 2-hour drive from Sapporo airport (Chitose) through the national park. It was quite a nice drive (albeit very busy), especially with the autumn colours.

The ryokan is understated and beautiful. The staff were very good and the food was excellent. The rooms are very spacious (about 120m2 or so I'd guess) with two 'gensen kakenagashi' onsen, one inside and one outside on the spacious deck.
There were some minor niggles (house keeping was not particularly impressive and I found the living room too sparse, even by minimalist Japanese standards; some ikebana arrangement or art works would not have gone amiss). On the whole though this was excellent - kind of what I'd hoped Aman Kyoto would have been like.