What do you keep your thermostat set to in the cold winter months?

I live in the White Mountains of northeastern Arizona (6,300 feet); during the day (if I'm home) I set the thermostat to around 66; at night, 55 (if night-time temps in the mid-20's to 30's) to 58 (if teens or below). When I'm gone during the day I use the night-time setting.