Steamboat Springs, in Colorado is probably where people go skiing. There wasn't much snow about when we were there, so instead I enjoyed the hot springs at dawn. They were actually quite cool compared to Japanese hot springs, but they did include a nice swimming pool, which is not something I've ever encountered at an onsen. Other differences - the bathers were less naked but more more mixed sex. It was too expensive for both of us to enjoy this luxury so James went for a dawn run instead, upon which he met a family of moose.
The Yampa river botanical gardens exceeded expectations, and were very colourful.