My goal is to be filthy rich and set my family up for generations. maybe I should pay the mortgages faster?

The investors that I work with find this much less risky and a much faster way to get to ROI. 

Quote from @Robert Ruschak: Would you skip the 700+ single family houses and scale up faster into multi-family?

I'll buy the fuel if you'll take me up!

Adding and making better could sell or rent faster, but it won't get you more than what the market ARV and rent is set at from other similar comps in the area....and your Interior Design background will help, if you you it mostly as an understanding of cost. 

Over the course of a weekend—and fueled by beer, food, and sledgehammers—we completely cleared out the space.

Selling and exploring a 1031 exchange could make sense if you can find a deal with stronger cash flow or faster equity growth, but the key is comparing your current return to what your skill and experience could generate in another investment.Here to help,Jorge

Wow, you are firing off questions faster then I can read them and they are all good, but pretty general.

That mirrors my experience too - our Hispanic contractors know exactly what the market rates are and they may be a touch below but not considerable - what you are getting these days is a faster, tighter job, not huge cost savings.  

Seems like they presented better, know the local area more and will get your property sold faster.