Most of the West Coast studios are in the San Fernando Valley, as others said.
Chatsworth has Wicked, VCA Platinum, Metro, Elegant
Angel And others. Van Nuys has Vivid and Evil Empire and used to have Extreme. Canoga Park has a whole bunch of them too. Woodland Hills has one or two. Northridge has a couple. Burbank and Glendale, one or two. Tarzana, Encino, same deal. All are in the San Fernando Valley.