I know most people still don't use phone lines, but I would keep phone lines in every room, with ethernet also in every room. I would do coax cable everywhere also setup so that it would be easy to either add cable tv or satellite tv in any room. I would renforce some walls, as I live in a quake zone, I would want to mount an 80" tv on a wall and not have to worry about it falling down in a big quake. I would set the house up to be wifi friendly as well. So that if someone wanted to know the optimal place to put this wifi devices they could, maybe a wifi shelf that was located high, had a place for the cable modem or dsl modem or whatever and plugs with power surge protection built in.
Now to the real tech. Smart thermostat. Something that could sense when I am home, maybe the thermostat was connected to sensors in the door that knew when the door opened and close and had heat sensors for detecting living beings in the room. Thermosensors? That way when noone is home the thermostat could automatically go to a low setting or turn off. I would add in smart heat / cool routing. Sensors to know which room you were in most often and allow you the option of having those rooms kept warm or cool at the temperature you liked and then other rooms that may not be used as much kept cooler. So if you spend all day in the office and use a particular bathroom, the tv room and bedrooms would not be heated up.
I would add in smart appliances in the kitchen. Autosensing range hood that could adjust speed of fan based on what was cookiing and how much steam / smoke was coming from the stove. An overn that would quickly warm up and could sense when things were taken out of the oven so that the oven was never left on by accident. If the oven was empty for 15 minutes or something adjustable then it automatically shut itself off. Smart refrigerator that could track what was in it by bar code and tell when things would expire. Option to turn it off or not use that feature.
Door and window sensors that could be connected to some central system to show when any window or door was open. This could be setup to tell the heat/cooling system to turn off if someone opens a window for more than x minutes to save energy. Setup for centralized IoT.
Solar built in with the possibility of wind turbine.