We want to go for another real-estate investment (we are doing buy and hold..buy low, renovate and make them short term rentals on airbnb in Ocean City, Maryland).

Used all the money plus brought in 20 k to make the rent low enough to make sense and be safe.

Some of them seem a bit too low.

>> Low fixed fees of $625. 

I have also found that since I am in such a competitive market (central Florida) that the rate is low enough on the 4-bedroom that I often get couples who could stay in something much smaller but find our house worth the slightly higher cost.

Whatever direction you go, don't buy in cheap, low end neighborhoods just because they are affordable. 

The problem with low end properties is the relative cost of repairs.

There are low end areas that offer easier price points, and high end, single family and large mult-family, commercial, storage, universities ... 

Your property taxes and repair expenses seem low and unless this is in the Seattle metro a 5% cap rate isn't the greatest on a triplex. 

In some properties I put electric baseboards from Lowes and I was perfectly content with the outcome.