We have Echo devices all over the house. All the bedroom lights and ceiling fans can be turned on/off by voice ("Alexa, turn the master bedroom lights to 10 percent"). I have a Logitech Harmony that allows me to control the TV by voice ("Alexa, turn on Apple TV"). My dad lives with us, so I have a motion sensor that turns on the hallway light to the lowest dimmer setting if he gets up at night to use the bathroom. Sometimes my dad will come home after I've gone to bed, so the front porch light is on an automated schedule so that I don't have to leave it on all night. We have outdoor landscaping lighting that uses outdoor-rated smart plugs to go on at sunset and then turn off automatically after we go to bed.
I use Ecobee smart thermostats. I've used Nest before, too. At some point, I concluded that I really prefer the Ecobee, but now I don't remember why. I can control the temperature by voice ("Alexa, set the upstairs temperature to 72 degrees") or just on my phone.
I have a smart sprinkler system that I got about 18 months ago, the Rachio:
https://smile.amazon.com/gp/product/B07CZ864Y9/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1. It's awesome. It drove me crazy when it would be raining and I'd forget to turn off the sprinklers, so they'd be on while it was raining. The smart sprinklers are connected to wifi, so if there's rain in the forecast, it won't run that day. It has saved me tons of water. Everything can be run off a phone app. It was pretty easy to install.
I have a Flume device that measures water usage.
https://smile.amazon.com/gp/product/B07GPXKN8Z/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 You put a sensor next to the water meter that uses magnetic field to tell when the meter is running and how much water is being used, so you don't have to actually connect anything to the meter. We had two water bills in a row that were way higher than normal, but when we had a plumber come to the house, he said we had no leaks. I used the Flume and the app to figure out that water was running somewhere. Turns out it had to do with water leaking out of our pool, and then triggering the automatic refill to the pool. The Flume will alert me if there's continuous water usage over a period of time, indicating a leak.
Other stuff: Ring front door camera. Garage door sensor that allows me to open the garage door from my phone (to let someone in if I'm not at home) and will alert me if the garage door is open for more than 30 minutes (because I sometimes leave the house and forget to close it). Probably some other stuff I'm forgetting.