Fixing the exterior, painting the interior, fixing the kitchen and the floors. 

Note you do walk through the kitchen any time you need to go ti the bathroom or bedroom

They all need new kitchens and bathrooms (plumbing included). 1 needs Mold Remediation due to corroding pipes in the basement.

 - One interior unit will be 12,000 BTU for a large living room/kitchen space, and a smaller 9,000 BTU for the bedroom.the total system capacity has to be able to cool both inside units at the same time so 21,000 BTU or larger for the outside unit.The beauty of these is that they can be installed DIY (provided you get your 608 certification card), as long as the line sets don't need to be shortened or lengthened, as there is no brazing/welding involved, just connect the lines and purge air, etc.my dual zone costs comes in at around 2.6k to 2.8k for my 800sqft structure.

Major improvements, like a kitchen or bathroom rehab, do not.

But a window AC tilted the wrong way can cause damage and definitely not in kitchens.

Just know the certain improvements have more of an impact on the value the others like kitchen and baths will have more impact and garages not so much. 

Get lawn cut, bushes and tree limbs trimmedFresh smellSpend rehab money where you get the biggest bang (i.e. bathrooms, kitchen, paint, flooring, fixtures, etc) vs roof, condenser, hot water heater, etc (assuming they are in at least okay condition to the untrained eye)

In addition, unit 2 has some basement space converted into an additional bedroom and bathroom and also an additional kitchen. 

Work I did myself: Installed new ceramic tile in the kitchen, basement, and bathrooms; painted; installed new kitchen appliances; installed new garage door; installed new screen door; updated landscaping; replaced water heater; updated bathrooms; added kitchen cabinets.