I would ask the current owners which room tends to stay the warmest. Also consider what direction the windows face, as a room on the south side of the house will stay warmer than one on the north side. My herp room is a south/west bedroom on the corner of the house. It stays at 79-80*F in the summer with the central A/C thermostat set at 76*F, and in the winter I simply close the door and run a space heater in it while the rest of the house can run a lot cooler.