I read every one of these posts, because it is illuminating to read other people's point of view and experiences. I can identify with almost every post, too, since I ride bicycles, motorcycles, drive tractors on roads, drive trucks, pull trailers, etc.
Once while riding my motorcycle on a 4 lane, an older gentleman pulled across the road trying to make a difficult left turn entry to the road. He obviously didn't see me until my headlight was inches from his face, which was frozen in terror after a maximum effort stop from my bike. There was no need to say a word.......we both had a lot to think about after he slowly gained his composure and I waved him on. I'm positive he simply didn't see me, and it's a proven phenomenon with motorcycles and a good argument for a flashing headlight.
Riding a bicycle with my wife after someone had been killed right near where we were riding, I observed two instances in one year of motorists drifting off onto the shoulder while distracted with texting or looking down at something in their car. One strategy is to ride slowly at the furthest edge of the bike lane away from the centerline, facing the oncoming traffic. (yes, I know, it wouldn't work in places that actually have bike traffic, and it is most likely illegal since the laws were made before cellphones took over the wheel) and look at every single driver coming toward you. If any vehicle is not centered in their lane, or is looking away from the road, pull onto the grass. For fast, hard core biking, this wouldn't work, (closure speed, thin tires going onto grass, trash run over at high speed,etc), but for someone riding slowly on a cheap mountain bike, it works. Also, in Florida, there are sometimes sidewalks, which, again are usually deserted because of the heat. Riding at a slow pace, and totally stopping or vacating the sidewalk when a rare pedestrian is seen keeps it safe for them. Also, I always go behind cars that are waiting for traffic to pull out onto the road, or at least make eye contact and almost always get a 'go ahead' wave from them.
I guess my main point that I need to add to this is that the 3 times that I could have been killed were not the result of anybody trying to drive aggressively, it was just common inattentive driving with no intent to endanger anybody. I have always seen courtesy from drivers while on a bicycle, except for once when a bunch of kids whistled and yelled at my wife.
I have seen plenty of people that must use bikes for transportation in order to get to work, either from bankrupcy, divorce, DUI, other licence suspensions, etc. So, let's continue to give bikes some room without any gestures except a wave. Those large gaggles of bikes hundreds of feet long on a winding 2 lane represent a real danger to which I can see no easy answer.......they are probably in a friendly competition, and are unlikely to pull over to let traffic by, but are usually going slow enough that the most impatient drivers in the parade behind will try a dangerous pass.
Back to the first post, my car hauler-width trailer is edge-to-edge across the lane on some of our underspec'd country roads and there is always some stress when an oncoming driver doesn't realize that, and crowds the centerline unnecessarily. Coming across a rider in that situation, I would have to slow to their pace until I had the entire oncoming lane free to pass.