When I have ridden on the famous SoCal motorcycling roads such as Mullholland by the Rock Store I have found the motorcyclists to be fairly polite. Much better than up here in the bay area. On climbs I move as far to the right as is safe when I hear them coming. If they catch me on a descent I'll move over and wave them by when it's safe to do so. They generally leave me plenty of clearance and I often get a wave in return for letting them by on descents.

They can only take up the entire roadway if you get intimidated and get off the road for them. There's no need to do that. They're not going to hit you.