New Asia has been in Chinatown since my mom first came over from Hong Kong. She said the quality's gone down since then, but its still a great place. It's probably the largest dim sum place in town so there's plenty of room (which is rare for San Francisco). The dim sum isn't that great but it is among my top choices in terms of SF Chinatown. I really recommend their Ha Gaou (Shrimp dumpling)...they have the best in town. Seating is plentiful, except on weekends, where the place gets packed by 11am.