I'm with Retro Grouch on this one, I always tell my guys to think in terms of "gear ranges" for the crank, and dialing things in more precisely with the rear.

I work at a university, and am constantly amazed at the numbers of kiddies who come to school with modern 24-speed mountain bikes-and don't shift. You'll frequently see them get off on the rather mild hills we have on campus and walk.