Metropolitan Oakland International Airport

Oakland's a good choice for GA visitors to the San Francisco Bay Area -- it's actually almost as close to downtown San Francisco as KSFO but it's usually quite a bit cheaper, it has a good selection of IFR approaches and a well-controlled airspace, it has a very large GA base with a 24 hour FBO (Kaiser), and it's close to BART and other transport options. I've been based here for years...