Northern CA and Southern CA are anything but "close enough". If you've never lived in northern CA you owe it to yourself to do it once (San Fransisco is not northern CA) north and east of Sacramento CA is a special place that has very few peers on the entire planet. Moderate winters, hot summers (but not the hottest and has plenty of water to cool off) less than two hours to the ocean or to the mountains. You can ski in the mornings and surf in the afternoon on the same day if you want. The people are waaaaay more laid back and friendly than southern CA and tend to lean more libertarian than liberal.
You want bright shiny, loud, obnoxious, intense, everyday go Southern CA.