Mathew, great advice, and thanks for letting me know what those units are called.
I googled PTAC units, and it appears they run approx $700-1000 per unit (for the ones that do A/C and heat), plus additional materials, installation, etc.
I would need to purchase and install 86 of these if we go this route and probably upgrade electric in the units to add more amps to run these. Sounds like a 120-140K job, but would allow for lower utility bills and can pass the cost directly to tenants for heating/cooling.
For oil, I checked and the last few years bills and they included maintenance they did plus propane they bought for the stoves (there is a big propane tank and it looks like it just runs gas for the kitchen stoves, nothing else).
It looks like I need to buy approximately 13,000 gallons of oil per year for an average winter.
I'll see if we can negotiate better pricing from the oil companies. If their margins are 60 cents per gallon, there is a lot of negotiating power there! I thought the margins were a lot lower than that.
Great info here, much appreciated.