Interior work included new doors, windows, flooring, plumb lines, paint, fixtures, heat pump, roof, bathroom and full kitchen remodel.

These homes are typically neglected for a long time before being abandoned, then they are shut down so you can't test the heating, plumbing, electrical, and other systems.

The pain is heating up, however, as our kids grow and expenses balloon.  

(Windows, heat pump, insulation, etc) Local utilities and cities may have additional rebates.it's worth looking into to help your bottom line, make the properties more cost effective for renters, give you a market advantage, and care for the planet.

New heating and air included in deal paint and fixturesWhat was the outcome?

We have tankless in our vacation home and it takes FOREVER to heat up unless we increase the heat and then possibly risk someone burning themselves. 

I'd love to do some larger updates (replacing asbestos siding and adding a heat pump would be AMAZING) but that's likely too over the top for the area that the house is in, and it would take way too long to make that money back even after we move out.

Updated landscaping, removed old baseboard heating, updated HVAC, new roof, updated kitchen, updated bathroom, added recessed lighting/fans to living room and bedroom.

Insulation, Sheetrock, electrical, plumbing, heat, cabinets, bathrooms, kitchen, appliances, roof, windows, paint, landscape, etc What was the outcome?

As for CapEX it would matter what type of heat you have, what type (if any) A/C you have, what type of roof you have and the sqftage, what appliances do you provide on top of the normal  fridge/oven (ie dishwasher/microwave/washing machine/dryer/etc)