Good locations for a thermostat include interior walls that do not get direct sunlight and locations where access to the thermostat for programming is easy. Thermostats should be in the center of the house on the first floor, and they should be 4 to 5 feet from the ground.
A thermostat on the second floor makes sense only if a house has a zoned system, in which case, the first floor also needs a thermostat. Thermostats should be kept away from doorways, windows and skylights, and furniture should not block them. A thermostat should be in a relatively low-traffic location; otherwise, it risks getting bumped or damaged when people walk by with boxes and other loads.