I always kill the AC in winter because here in the northeast, cool damp weather, even when warm enough to allow the compressor to come on, makes the defroster chill the windshield so much you need the wipers, and it means you have to run the AC 100 percent of the time to keep the inside free of fog even when all you really needed was a little whiff of lukewarm air to clear it. Besides, it's handy to have all the multiple-outlet settings available for heat. I just unplug the connector at the receiver dryer up near the firewall, because it's easy to reach, and easy to reconnect every once in a blue moon to keep the compressor happy.
I have considered putting in a switch, but have been too lazy to bother.