What constitutes the north bay? I've been to Marin and Sonoma counties and like them both. I go to SF every now and then, but I just never stop in SV although I

What constitutes the north bay? I've been to Marin and Sonoma counties and like them both. I go to SF every now and then, but I just never stop in SV although I drive through it. My priorities are different from 1999. And while I no longer wish to live in SF, I am still avoiding SV. The primary reason is price.