I'd second (or third) NorCal. My office, when I started there, backed onto the Pixar campus in Emeryville. Specifically their outdoor pool. The pool was next to their soccer field…
I lived in North Oakland (almost Berkeley) and rode every day. Joaquin Miller, Redwood, Annadel, Skyline, China Camp, Camp Tamarancho - all within a 30 minute drive all with excellent, largely un-used singletrack. Think 5 x 5 all mountain riding.
Mind you - cheapest living we could find was a dodgy studio apartment for $650 a month…in 2002!
You are also on the doorstep of the Sierra's and Tahoe. Nevada City is an awesome MTB destination - with many more all over. Squaw Valley?
Micro-brew's to blow your mind, good food and made lots of friends.