End battles over the thermostat by putting your control in your pocket—specifically, in your smartphone. This is one of the many benefits of the EcoBee wi-fi thermostat ($250). Additional benefits: you can buy multiple sensors thus allowing you to manage the temperature in multiple rooms, the sensors can tell which rooms are occupied and adjust accordingly, the unit will lower temperatures automatically when you’re not home, it also knows the temperature outside and will adjust accordingly, and you can set the schedule yourself. Oh, and you can get a professional installation. Just in case.