Marin county is a poor choice if you want to build things. They are extremely uptight about permit enforcement. Sonoma is easier.

I'm in Solano, which is somewhat ok. We still sometimes struggle with the permit department. It would be even easier if we were about a mile north, in Yolo. But there isn't a huge inventory of properties for sale so you don't necessarily get to pick.

On the plus side, if you're trading in from a home in the inner bay area, everything will seem very cheap.