I think the entire state is either urban or suburban at this rare, with a few properly rural counties in such as Shasta, Alpine and El Dorado/Placer/Nevada Counties.
Of course, I am not from there, so I cannot truly fully answer this question.
Not counties per se, but certainly sections of counties. Counties in Western US are much larger than in East so many in are a mix. Riverside county has a mix of urban, suburban, exurban, and rural. Ditto San Diego County. Exurban tend to be more east of the Rockies where counties are much smaller than West of it where larger thus often suburban and exurban are same county just different sections.