I made this same decision just a few days ago. I had planned to free-range during the day, and coop at night. Then I had a talk with my neighbor, who allows his flock to free range. I have seen coyotes near my area, but wasn't worried because of my property fence, but my neighbor clued me in to the dangers of predators that I don't often see or notice, like oppossums, bobcats, and snakes, not to mention birds of prey such as hawks. The vultures we have here will attack chickens, and my neighbor claims to have lost a hen to one. Houston is not far away, so I imagine you'll have some of the same dangers there. I would recommend that you figure the price of a run (Most of the savy people on this forum recommend 10 square feet per chicken), add in the price of any additional feed that you'll have to buy, and balance that against how you (and others in your house) will feel if your best egg-layer is attacked. Needless to say, I built a run for mine.