Which airport should I fly if I go to San Francisco Bay Area?
There are 3 major airports in San Francisco Bay Area: San Francisco International Airport (SFO), Oakland International Airport (OAK), and San Jose International Airport (SJC). They are located in different areas in Bay Area and serves different neighborhoods.

If you are flying to San Francisco or Peninsula area, San Francisco Internal Airport is the most convenient airport. 

If you go to East Bay, such as UC Berkeley or Oakland, Oakland International Airport is the best option. 

If you go to South Bay, such as Palo Alto, Mountain View, San Jose, then San Jose International Airport would be your destination.