I don’t get as much into automating for the sake of automating. Personally, I prefer technology that makes my life easier. Anything “smart” in our house has to be manually overrideable.
That said, one thing I’m working on automating is the HVAC. Eventually I’ll have the Central heat, central humidifier, and whole house fan controls all integrated with HA. My goal is to maximize both comfort and energy efficiency. Being able to maintain the comfort level by automatically switching between A/C or fresh air (via the whole house fan) would be pretty cool (figuratively and literally).