Idaho has some of the most and best hot springs of any other state. As soon as you get into hot springs territory you can hit a few in one day with determination. I LOVE them. My hair and skin always feels amazing for days after a god long soak.
If you love skiing or snowboarding but don't like to battle the crowds of people, you can be the big man, or woman, on the mountain and own it out right for the day. You just have to find about 100 people you wouldn't mind spending a day with.