I'll pretty much wave at anyone who waves at me. The way I see it, they are waving for a (positive) reason, so returning the wave will make them happy. I remember when I drove an old Honda - I was new to riding, and waved seldom-every once in a while a guy on a H-D would initiate a wave to me, and man that made me feel cool! If I can make someone else feel that way, I'm all for it.
