I don't know where this is heading.  I'm sure we're all aware that a successful poster will get the most people into the course.  I admit, I do not know what poster would accomplish that.  

If it's only going to have a slogan such as those listed in this thread, I'd like to remind everyone that the "business card" (see attached) that we just made and  into which many BB members put a lot of work has the slogan, "Lose Your Fear and Learn to Ride with Confidence".  

We also have the ad (see attached) that we ran in the newspaper that had the slogan, "Rediscover the Joy and Freedom of Riding Your Bicycle".  If we're just going to have a slogan on the poster, that could be a poster as is.  (I know Ryan, you don't like the kid.)

Finally, we also have the first of the billboards (see attached) that has the slogan, "Same Roads, Same Rights, Same Rules".   Perhaps that could be made into a poster even though it's purpose was more to be instructive than to attract viewers to sign up for training.  Perhaps the poster could say, "Same Roads, Same Rights, Same Rules: Learn them!  Sign up for Confident City Cycling"