The current plan my contractor has is ~4' of mulch on the perimeter, a clean brick outline maybe like this, and gravel for the main body of the yard.

@Gary Baker I'm in your back yard in Fort Worth.

As far as a feature to make the propert stand out, do you do something like a back porch if no other houses have one, or a water feature in the front yard, or seller pays closing costs... that sort of thing? 

How big is the back yard, could you plant Leyland Cypress trees to cover the negative aspects, of put up a privacy fence?  

And he has asked if I had any other vacant houses because he has other guys at the yard that want a nicer place . 

. - Toys, and other belongings on the Deck and lawn/patio/outdoor areas must be organized and not lay all around the property/yard.

It probably needs only 5-7K just to clean up the yard, which is huge, and any other variables. 

The next door neighbors visibly treat their property like a junk yard (cars, equipment, etc.). 

Of course it's nice knowing that the exterior of your unit, the yard, pool etc. is maintained.

Where is the fence in relation to the house and yard of your rental?