Georgetown Yoga is a great studio right on the C&O Canal in Georgetown. It's small -- just two rooms (one for classes and the other for storing your shoes and coats and checking in) in a three-story office building. But it's a very beautiful and welcoming space.
They offer a lot of different kinds of classes, from the more active Ashtanga styles to pre-natal and post-natal classes. They also have fantastic clinics and they draw some pretty famous yogis for weekend sessions.
The studio also has some nice logo shirts and sells Prana-brand yoga pants, which are super nice.