Regular LocksAs a locksmith I have used and repaired  Kwikset SmartKey locks.

The end goal is to have something so we can leave behind even after the rehab is done. 1) change out locks when key is missing; Kwikset smart key, it can re-key seem to work fine.2) security system (monitoring or just stand alone) Camera would be nice. 

Anytime a tenant moves out I just rekey it to a new key.

Drill the lock or call a locksmith.  

Some places will require you to re-key the place to match their system, and some may require their photographer to go in and shoot the place ext ext. 

@Dylan KatzI would look at Kwikset 99390-004 Halo Wi-Fi Smart Lock Keyless Entry Electronic Touchscreen Deadbolt Featuring SmartKey Security, Iron BlackThis gives you both the ability to use code entry but also allows you to rekey the lock when the tenant moves out.

The sheriff in my county refuses to take investors inside the building so you will either have to contact the owner (the best way) or hire a locksmith (not recommended as this may be "bending" the rules in your area).But... if you can get the inspection before it goes to auction then you should have no problem closing within 30 days.

They make rekeying a DIY job, and I have a master key for all of the units.

If you use a locksmith to pick lock then enter, inspect to determine if evidence of use.Locksmith will not damage lock.

More expensive to buy at first but takes seconds to rekey.