The cost of living is obviously a big factor, but I've only been to California once (San Luis Obispo for a few days and drove up to San Fran for a few more), and I have to say, I absolutely loved it. Most beautiful part of the country I've visited (still have to make it to the Mountain West). If it were me, I'd pick San Diego in a heartbeat. Of course, living in New Jersey isn't cheap either, so maybe I'm just used to it.
