Check out Cherry Creek State Park. It is on the south side of the metroplex, but a very pretty park. In the middle of town and you will think you are in the country.
We like Cedar Hill State Park on Joe Pool Lake. It is 26 miles from downtown Dallas. They offer quite a few 30/50 amp sites with a large number of full hookup sites as well. It is a good clean park, great fishing on Joe Pool Lake (or boating), and ...