I usually try to pace the other roadies out there (not draft, just pace at a comfortable following distance) to observe pedaling form, hip sway, fit, etc, if not also to have an unofficial way of guaging my abilities compared to others.
Although sometimes the attempt to pace leads to the inevitable mischevious desire to pass, but its usually got more to do with how comfortable I am pedaling at the cadence/gear necessary to match speeds. if I'm bored or soft pedaling too much then of course I pass them...I didn't go out on a ride to coast.