I've been using a Netatmo Welcome camera. I keep it in the hallway near the front door (not in the guest living space).
It has facial recognition, so it knows the people who are regulars in my house (me, BF, friend who helps with cleaning, etc.). It's has a lot of flexibility in terms of alerts and who it records. For example, it knows me and just records when I first get home. Right now it records unfamiliar faces (guests) but doesn't record "any movement" (which was usually the cat walking by). It can remember up to 16 people, so while I sometimes teach it my guests (it helps me remember who is who!), I have it "forget" them after they've checked out. It also picks up on alarm noises, so let me know when some guests set off the smoke alarm.
I've also got a SmartThings sytem and keep a movement/temperature monitor upstairs. The upstairs in my old house gets much warmer in the summer than the downstairs -if it gets warmer than 76, I get alerted & can check in with my people to see if they'd like the AC on. I also have a open/close sensor on the door separating the guest area from my personal space, so if anyone were up to no good while I'm away, I'd know.
The Kwikset 910 lock works great, too. It's a simple re-programable lock - takes less than a minute to reset the code for the next guests & I don't have to deal with lost keys. (I do keep a hide-a-key for the 2% of Luddites that can't figure out how to work it!) The $99 version has an open slot to add a Z-wave controller that would work with my home automation setup, but I haven't felt a need to add that $100 piece.