Sorry if this has been said. I would go with the least expensive Nest(s) and download the Home app. I have a more expensive version. But I bought the less expensive one for my GF's house and it does everything I need to do, and do, with mine. If I ever need another one, I will go this route.
The key features I like are:
1. It's 7 day programable where you can put several different changes per day if you desire and along with that you can program the away temperatures and min/max (emergency) temps it will let the house get to.
2. Easy to switch from summer to winter programming. I think there's a smart mode where it supposedly knows, but I haven't tried it. I'm worried in late fall and early spring the weather is too erratic by me.
3. Easy to change the temp manually and in the app.
4. Tells you when to change the filter
5. Will tell you if there are other problems. For instance, it told my GF it was taking too long to get to temp. I took a look and found her filter filled clogged with her dogs, 2, hair. This summer's heat and her wood floors made it easy for the intake to suck up the hair.
6. It's plug and forget. Except when you get the message to replace your filter, or something else is wrong. Also compatible with android, apple, siri, alexa, and google.
7. Finally, the best part is it works with your phone, or all the household phones, to do geo fencing. Therefore, when everyone is gone, it will automatically go to your set away temperature and vice versa when anyone comes home. Another plus is on a real hot or cold day you can turn the system on from the office so it will be at temp when you get home.
Basically, in use I just program an awake/day temp, a colder/night sleep temp, and let the geofencing turn it to my away temp when I'm gone and back to the normal programming when I return. Which is why I don't care about all the other smart/learning features.
