Pacific Repertory Theater at the Golden Bough Playhouse will have Monty Python's Spamalot, which opens this weekend. That should be a lot of fun. The theater is on Monte Verde Street between 8th and 9th. It's within walking distance of the business district, but it's kind of a dark forested neighborhood, so you'll need a flashlight to find your way if you're on foot. http://www.pacrep.org/ Showtime is 7:30, though, so it may be too early.
Sunset Center for the Performing Arts (San Carlos and 9th streets) has a symphony concert at 8:00 PM on Saturday the 23rd. www.sunsetcenter.org/event_calendar.htm