For your very finest fine art pieces, bring them to Painter's Place in Hayes Valley. Prices are expensive but Painter's Place is THE place to go for primo framing and an eye for design in San Francisco. They have framed several pieces for me, and really came up with creative approaches. The owner, whose last name happens to be Painter, sells his artwork on the premises. I think they also have a Marin County location in Larkspur.