One of the best cups of coffee in San Francisco is at Four Barrel in the Mission. Seeing the latest art on the walls there is an added bonus. They have exhibits that come and go, but in the two front windows you see 2 pieces that never leave - the Knot Lights from local artist/industrial designer and sustainability champion, Seth Quest. These are giant displays that probably weigh a lot but actually look like their floating in the air. I'm not sure how he made these, but they are so impressive and functional much like his other work such as the Recession Desk Lamp and the model for the ever efficient Soothe Bath.
Four Barrel Coffee, 375 Valencia St. San Francisco, CA