For the most part its road only and save the sidewalks. But it is extremely area-specific. I've mention this on other threads and sidewalk cycling is accepted and almost the standard here in Pacific Beach San Diego. All you see is mostly beach cruisers, I have a few co-workers that sidewalk commute.

Generally its an accepted practice here. I tend to take the sidewalk over small stretches, especially this specific two-lane section that has horrendeous road conditions.