I grew up outside of Dallas and camped at Tyler State Park lots of times. We liked it there. There were plenty of trails to walk on, and the camp sites were level. I think that they were mainly pull-through sites, but I may have that part mixed up with another camp ground.
As I recall, the showers were also reasonably nice and clean. However, the last time I went was almost 10 years ago, so that could have changed.
The zoo in Tyler is pretty good. It's not quite as good as Dallas or Ft. Worth, but they were doing a lot of improvements the last time I was there. It was also free.
<img height=100 width=100 src=http://www.muppets.com/images/kermithead.gif>