So i’m trying to figure out how to lock the door when I leave the house.
I don’t want to bring a key with me or reach for my phone each time. How can I lock the door when I leave?
I was tempted by the auto lock but have visions of me getting locked out with my phone in the house.
I must be missing something simple?
You can get a push notification and be asked if wish to lock the door, after leaving your home zone. Or you can use a home automation system like Home Assistant and auto lock via rule after the last person has left the house.
A third way is to use lock and go.
But your nuki alone can’t know if there are still other people in the house after you leave the home zone.
I have a Keypad 1.0. The last person to leave the home locks the door by pressing the back button on the Keypad. That also automatically activates the alarm of my OpenHAB smart home system and triggers many more automations, such as turning down the temperature of the radiator valves during winter, turning off the lights, sound system, TV, wall plugs, etc.
My wife is very reluctant to changes, but she adopted the keypad and the lock almost immediately.
Looks like i’m getting the keypad then 
Good idea. If you want to increase the WAF take a Keypad 2.
If it should be invisible Lock‘n‘Go (double press on the button on the Nuki) works very well. Locks the door 20s after you left or immediately after the door closes if you add a door sensor.
WAF →
Nuki button → I have a small child, so buttons he can reach are a no-go.
I consider Geofencing an insecure setting. There’s enough time for a potential attacker to gain access before anything is locked.
I believe the best option is the Keypad. You are sure the door gets locked right when you leave.