For dim sum will echo what has been already mentioned - for sit-down dim sum the Koi Palace affilliated restaurants (Koi Palace itself, Dragon Beaux, and Palette Tea House) all have very good dim sum. Palette Tea House has the added benefit of having cocktails if you’re into that, and as also mentioned is in the tourist attraction Ghirardelli Square if you feel like doing some sightseeing. Of other recent dim sum lunches I’ve had - Harborview in the Embarcadero was pretty good too.
