I went to Covington Multicare's PT department for treatment on my herniated disc (L5-S1) in my lower back. The physical therapists there were all incredible, although I recommend Keith Boyd over the rest.
It is a bit removed from Seattle, but Keith has a great focus on a combination of stretches, balance ball, weight training, and more.
I went from not being able to walk or drive to being able to with a minimum amount of pain. The pain is slowly going away, and I attribute it 100% to these PTs. I've taken next to no pain relievers (they don't work well for me) and almost no muscle relaxers (although I have had to now and again.)