Hardware Pick: August Smart Lock
Stacey Higginbotham's thing of the week on This Week in Google 425 is the August Smart Lock. This has an updated form factor from previous versions, and it's Bluetooth and Nest enabled. It doesn't work over Wi-Fi without an extra $79 bridge, however.
As locks go, this is really impressive. It is very sturdy hardware -- the lock itself weighs at least a pound. It also has Door Sense, so for if the door is open but the lock is closed, it will still report correctly that the door is ajar. The new August Smart Lock is quick and easy to install, and installs with your existing deadbolt locking mechanism so your key would stay the same.