As a former waitlister I am a huge proponent of people telling schools their decisions as soon as they make them. I feel like the polite thing to do during decision time is send them out as soon as you know -- it's dragging on enough on its own.
Try to sit down and figure out where you're going after your visits are over. Those accepted off the wait list have only a relatively short time to find places to live (a lot is snapped up before even summer), job searches for significant others, etc. Be thoughtful and rational, indeed, but don't run out the clock for the heck of it.