I went to a Beginners yoga class. It was wonderful. We stretched and stretched and stretched! The poses were just challenging enough to make it work, but not so hard that I couldn't do it. I felt so loose afterwards, it was like I had just had a massage to loosen all my muscles. The teacher was great--very gentle and helpful.
I tried a Yoga class once before years ago, and it must have been an advanced class or something because the poses were so difficult that I spent all the time just trying to get into them without ever enjoying a stretch from them.
There were all different shapes and sizes of ladies in the yoga class. They weren't all skinny bean poles. I recommend it if you're looking for a low impact strength excercise. It made me feel great which helps me have more motivation to work my OA steps.