As Bill Thomas says, “the greatest amenity in a senior community is community”, so investing in things that will promote togetherness and cooperation are high priorities for the population that I am addressing.The funding model also relies upon bringing together different groups and structuring deals to meet their diverse objectives.

That's not to say you can't do well there, but I'd encourage you to look at Belton and Temple (which can also be very rough and block to block) rather than Killeen.The good news is that there continues to be serious population and job growth in the area.  

To pick a location, I understand I want to evaluate median income, a large population of those approaching retirement age, and a decently dense population.

It was put in place because the feds have increased immigration for the last ~10 years (over 5M people or 8% of our population) to the point that we now have a housing shortage. 

I'm guessing because the population density is higher with more neighbors and all that. 

For LTRs, prioritize markets with population growth and strong job markets.Wherever you choose, work with an investor-friendly agent who knows the local market and can help you analyze deals.

I'd suggest checking in with some social service organizations within a few miles of the property to see if they work with people/populations in the area looking for this type of house.

Growing population, great employment opportunities, steady appreciation etc.The best amenity has been location.

Screening is definitely an area I studied up on beforehand, and having a large graduate student population to choose from definitely gives me more confidence.

Chicago isn't going anywhere.Compare that to other cities in Florida, I think the population growth is amazing but long term with hurricanes/climate change, it will be harder and harder to own there.