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 ...

New lighting, ceiling fans, flooring?

Upgrade units that have carpet to wood flooring do basic cosmetics to units that need it, and build the 2 units in the empty basement.

This is based on what you describe to me.Attic insulation should be R60 above ceiling and below floor R30 in your area, I doubt yours meets this standard.

.: paint, new carpeting, refinish hardwood floors, etc.I would like to try to sell it myself.  

I had to redo all flooring, leveling etc.  

Really mixed on floor.

There is also an unfinished large attic area.I have an option to dig down the ground and bring basement ceiling height to 7'6" and duplex down from 1st floor for large unit 1 and then duplex up for a large unit 2.I have another option to try changing zoning from current RS3 to may be RT-4 or something so I can make the basement as legal after I dig the ground so building can be legal 3 unit.The building is surrounded by B1-2 zoned building and it seems weird that only this building is RS-3.

The home has all solid hardwood floors in all rooms but the kitchens, bathrooms, foyer, and basement.

The stucco is cracked out the outside and I think there may be just a leak on a wall from a balcony on second floor.