Where can I go within 3-4 hours of SF that has a nice hotel with a hot tub, heated pool or hot springs?

Ideally, there would some fun stuff to do nearby, towns, shopping, hiking, beach. Nature is preferred to town. The hotel should be open to kids but not necessarily “kid friendly.” Have a little money to spend so I’d love to find a really relaxing, natural place to rest up in with my family.