One effective strategy to maximize unit potential is to explore opportunities for adding extra units, especially in C-Class properties.

We have pulled permit for one STR, like air B n B and have furnished one of the units.

How much of the 52 units do You own? 

The picture they have on Zillow vs one of the several I have with the same view:Your pic is better than the PM's pic, but that pic isn't why your unit hasn't rented. 

I'm trying to analyze my first property and not sure how to set it up to run the number using the calculator tools here. 2 of the units are successful Airbnb short term rentals, and the other two units are month to month rentals to existing tenants.

You mentioned that you've been paying water / sewer for all 4 units. 

Being 3 units, the valuation will come from comps not from cap rate/ income based approach.

I used a hard money loan to purchase this off market deal.I rehabbed the upper two units within two and a half weeks and have a renter already lined up for one unit.

That fills your unit for the winter and buys you time to prepare for the next time.

two things I have learned.  1,200 is a sweet spot for demand, and if you do have a large unit of 2,500 get a couple of them zoned for auto.