I'm sure the snarks on here will say the best tenant proofing is good screening before you rent  :) I personally like tile floors...I have given up on wood...laminate and carpet...provide extra air filters for the AC unit (unless you use replacing them as a reason to go by and check out the place every few months) fire extinguisher in the kitchen...make sure smoke detectors are installed and working properly ...if it is a single family be sure the tenants know where and how to shut the water off ...

Maybe they want a new fan, or a motion detected security light-- show them you aren't just raising rent, but you're actively improving their homes.   

If gas is at the property you need a proper detector anyway.