Visibility is key In Washington the pamphlet they put out on bike laws and safety even state that you are to be visible to cars at all times there is no requirement to stay as close to the curb as possible that could really be un safe.
In the Seattle area we are allowed to use sidewalks I only do in one case on the way home I use a stretch of sidewalk rarely used by pedestrians to avoid a bunch of angry drivers and a couple of lights though I have to be cautious of cars coming out of the Adobe building without looking both ways. and the occasional car that pulls so far forward they block the sidewalk and bike lane in the street (I am going against traffic so I cannot legally use the bike lane). Otherwise I stay off the sidewalks they are for pedestrians not vehicles.