Amarillo is nice enough but it has lots of cattle lots. When the wind blows a certain way the entire town smells like a cow's ass. Friendliest people I've ever met though.
Dallas/Ft. Worth is one big concrete jungle with hardly any greenery. If you had to choose between the two, Ft. Worth has the better downtown.
All the large Texas cities have bad air problems in the summer. When the air doesn't move the air quality is bad enough to give you a headache and make your stomach feel slightly upset.
Housing is cheap here compared to other U.S. states. You can get a decent three bedroom home for 130k here.