I had some pipes along an exterior wall in a vacation home in Wisconsin freeze and break several years ago. No fun. We were away and thought the house had enough heat. (About the same temperature some of you keep most of the time, LOL). We thought wrong.

Most of the insurance sites say that one should set the thermostat no lower than 55 degrees if you are away. I suspect that, depending on the part of the country in which one lives, that should be sufficient most of the time. The only time we ever had a problem was when the outside temperature was below -10F for three days in a row.