Offering a streamlined process, no repairs or renovations prior to selling, no market costs or agents fees for my family member, in return I will gain invaluable experience in the market and in the field along with providing my family with wholesale services.

Give investor a 10% return.  

If you really want to get rid of them, sweeten the pot by offering to return their deposit after you verify the unit is empty with no damages. 

I did attempt to get a quit claim deed from the other party but he didn't return my calls. 

They get a higher return since they are covering housing cost, have the $250k per spouse primary residence deduction in gains, is a savings account, higher leverage position, lower interest rate possible, will pay more premium for location, etc.House might be overpriced for REITs but not for home owners.  

Out of curiosity would anyone be willing to share any experience with non-paying renters who've vacated the property prematurely?

I've narrowed down the best return for my money in this market to a 2 bed/2 bath (with top tier amenities) - about 500 total 2/2 listings.I'm finding myself a bit stuck when analyzing why certain properties are making so much higher than the average listings when they seem to have very similar locations, amenities, style, flow of home, beds/# of people they sleep, reviews, number of reviews, etc.

I have also told my grandma who was getting 5% return in a CD that I would give her 6% if she lent me the money for the down payment on the last property I purchased. 

If there are non-residential (e.g. retail, etc) we would love to learn

Simply put the risk of a non-renewal costs more.