Very nice thread. Thanks, Dep!
I commute, ride for fitness and run occasional errands. I generally avoid medium-to-heavy traffic, but dive in and take the arterials when I'm going someplace new and don't know how to navigate neighborhood roads to get there. Know what's surprised me? The less-traveled side streets have generally (but not always) provided shorter routes. Who knew?
About a year ago, I started commuting again after a break of about 7 years. (I stopped regularly biking to work soon after some idiot threw a soda at me as I was riding down the shoulder of a highway on my then-12-mile commute home.)
Where I live now, it's a 3-mile ride to work. To start with, I rode the sidewalks along arterial streets. With the help of what I read here and on other Web sites and with the example of bike commuting friends, I moved into the streets. Depending on the situation, I will still act more like a driver sometimes and more like a pedestrian other times. I think I'm more thoughtful and careful now about when to do each.
I slow down for but ride through stop signs and red lights when no traffic is coming in any direction. When there are cars, I stop and wait my turn like everybody else, and I take the lane. (I will move over to let a right-turning car get by me if the turn signal is blinking and I'm the only thing keeping them from turning right. Seems to help keep tempers down.)
My biggest peeve is drivers who pull around to pass me right at a stop sign, so that we both come to a stop together, only to both pull into the intersection together. (Out of fear of right crosses, I hang back until I know they're not turning.)
Anyway, thanks to all who have posted good advice here. And to everyone who's passionate enough to argue. I came to learn, but I stayed to watch the throwdown debates.