I recently had a thought, don't know if it would do any good though - I'm an early bird, up before most chair hogs, this is where it came from. My thought was to bring some large sticky notes and a black marker and sit and eat my breakfast while the chair hogs begin. Then put the time on a sticky note and put it on the chair right after they left. This way, anyone walking by could see how long it had been vacant and act accordingly. Maybe the chair hogs might get the hint too? Would it work?? Who knows, maybe it might embarass some enough to stop, or at least get back to their chairs quicker.