Dots,
I don't know about Charm City yoga, but Greater Baltimore Yoga Center in Timonium is super. The founder is a physical therapist to boot. One of the instructors has had injuries of every sort -- there are women there with neck, back and knee injuries, and the instructor is very aware of the sorts of accommodations they need since she has had them too, and knows all kinds of ways to the the exercises that make them feel better. This fall I had neck and back pain following a very grueling trip to Chicago, and she had me feeling better pretty quickly.

You really need to go to a yoga center, not a gym, to get the most from yoga. I've done both -- I started with "Lilias, Yoga and You" on TV in 1976 -- anyone remember her? But you need a teacher to make sure you're getting all the benefits -- and not hurting yourself -- by doing it correctly. And the yoga teachers at the gym seem more intested in doing something quickly, rather than correctly.