The back, newer part of the house, which we use the most now that all the kids have moved out 72-74 during the day, 68 at night.
The front, old part of the house, that has it's own furnace and my sewing room 74 when I'm sewing, 68 when no one is in that part of the house.
The last 2 winters, here in Ohio, we've had something happen that hasn't happened in the 35 years we've lived here - the pipes to the upstairs bath, in the old part of the house, FROZE.
My husband built an airtight panel that we open when the temp is forecast to be -10 or lower. We close it in the morning, and it gets closed on those extremely frigid nights (the pipes are behind that panel)