Don't know about the spa, but DH loved the Fitness Center. He was there at 6am 3 mornings on our last trip. I think that was one of the selling points of SSR.
It is utterly fabulous!!! My favorite part of SSR!! DH and I love the fitness center and the spa is even better. Try it, I think you will like it! Even when we are staying at another DVC we will do our best to get to SSR spa and workout at least once.