Back on topic: there isn't much to add to this thread. If you don't want to tip, don't use the service. Park your car across town in the metered lot instead of using valet ;-). I firmly hold on to my bags at the hotel so they don't take them from me expecting a tip. Also when getting off the airport shuttle bus I handle my own luggage to make sure a tip is not warranted. (It is much debated whether a tip is appropriate in this case, but I feel better about not tipping when I'm not using any extra assistance.)

I staunchly hold off tipping hotel staff when they walk me to the room at check-in even when they hang around waiting for a tip. You can't avoid that service but my conscience allows me not to tip for it.