I think Raspberry Pi.... and my thoughts wander to robotics. Of course robots are the last and greatest evolution of automation (at home or anywhere else).
When I first retired... I played around with a deer chasing yard rover. It was a solar charged, remote controlled, mobile camera platform... with a buzzer and lights. I had hoped to get some automated control of the rover using radio signals and a PC located separately inside the home. My successes were moderate and very limited... at best. I disassembled my project after a few months. Although... I have continued to acquire parts and pieces.
But technology... particularly with the ]Raspberry Pi... has grown so much in the last seven years. It is tempting. I think for anyone with too much time (and too much money) on their hands... robotics is the perfect hobby. Otherwise... useful progress would have to be a within a team based approach.