If you are looking for lots of trees that I can recommend Daingerfield. Almost all of Texas SP can be packed on the weekend, but Daingerfield is small. Not to many campsites and can be quiet during off-season. And a small very clear lake and no power boats!!!
I also love quite campgrounds. I don't mind the "noise" fom the neighbors. But I don't like the noise from too much traffic and power boats.
You can rent or bring your own canoe. I love it. About 3 hours east of Dallas.
http://www.tpwd.state.tx.us/spdest/f.../daingerfield/
Another small park is Bonham. Only about 20 camp sites. Small lake. No power boats.
Another campground I came across about 2 years ago is along the Talimena Scenic Drive in SE Oklahoma. Maybe about 4-5 hours from the DFW area.
http://www.byways.org/browse/byways/2485/
http://www.talimenascenicdrive.com/
There is a nice campground on the Oklahoma side. I did not camp there but checked it out. It looked really nice. Lots of forest, great views ...
http://www.talimenascenicdrive.com/a...r_winding.html
One more comment to the LBJ grass lands. We have been there a few times. Group camping. The valley view camping area is nice. No facilities. Just some primitive but clean rest rooms. No electricity and you have to bring your own water. And very, very quiet.
The campsite is shaded but otherwise there is not too much forest. More grasslands like the name says.
But it is nice. Lots of hiking and biking trails.