I recently picked up a copy of Sally & John Woodbrodge's San Francisco Architecture: An Illustrated Guide to the Outstanding Buildings, Public Artworks, and Parks in the Bay Area of California, which is in a new, completely revised paperback edition. The book is more a catalog than a guidebook, with extensive information and photographs (over 600!) of a huge number of noteworthy and technically significant structures throughout the city. I grew up in the Bay Area and have spent a tremendous amount of time exploring the city on foot and bicycle and I was still amazed at how little I knew about its rich and varied architectural tradition.
The book covers new and old structures, including homes, commercial and even some industrial buildings, public art, parks and other engineered spaces. It's definitely a must-have for anyone interested in San Francisco architecture.