Hi - I am looking for recommendations on where to take some out-of-town clients for a business lunch on Sunday. I am looking for a restaurant that is impressive but not extravagant, unique but not too experimental, comfortable but not stuffy, and distinctly San Francisco (or California). A place within walking distance to Union Square or near Moscone would be ideal. I am considering Grand Cafe, Farralon, and Scala's, as these are actually open for lunch on Sunday. Any other ideas? Thanks much!