You hit a nerve Tom. I have a distinct delineation in my mind when we invite people out on the boat: There are sailing guests and social guests. The few guests who are really interested in sailing are told "OK -- you're either crew or you're in the way".

Anyone who's there for the "3 hour tour" is (tactfully) told where to sit and when to move, and everyone is given a safety briefing including where not to rest hands (e.g. winches and traveler tracks). I don't even try to focus on sailing if the cockpit is loaded up.... under that circumstance I'm happier if we can just anchor nearby, get out the food/beverages and people lounge on the nets.