Do you manage the adjacent units in question as well? 

If this is an office building adjacent to a large hospital campus, even better, as it is very uncommon for hospitals to close down, so you will likely have strong long-term demand.Given the occupancy, you don't have any real upside beyond rent growth over time.  

I would add Flower Mounds to consider if you are looking to be close to the airport too.However, investor friendly areas are Fort Worth which is growing a lot.All depends on your needs.

My goal is to find places with a range of 30-45 minutes of an airport.

It is a townhouse and the adjacent property (that previously had an identical interior layout and size) has gone through a renovation to expand the kitchen by approximately 100 sqft, and add a second bathroom.This adjacent property is currently renting for $300-400 more than what I believe I can rent my property for.

Airports matter.I would also give up on the whole VA or CRM approach to finding opportunities. 

The airport expansion is one of Middle TNs largest projects at the moment (private and public) and after the project started, planning realized it wasn't big enough.

@Rajesh Rathi Hey there, I am from Rocklin which is adjacent to Roseville.

My ultimate goal is to build the duplex on the adjacent land and househack.

I did a duplex renovation did fine. very strong urban core market strong appreciation, we see new build activity there, I would stay north of 104. we would build around there and we only do urban core or urban core adjacent in columbus. look at new construction if you can't find inventory you like. plenty of lots all good appreciation in the urban core, strongest rents.