I know that the Ouachita Trail isn't part of Texas, however now looks to be a good time of year to hit parts of that trail.
I went out with a few folks this past weekend and started from Talimena State Park in OK (the beginning of the trail) and hiked in a few miles. Water was plentiful and the temperatures were near perfect (60s during the day and 30s at night).
You have a pretty good climb at the beginning plus a load of rocks to hike over but then the trail smooths out. We encountered three other groups of hikers and we were able to grab a nice flat campsite along a well-flowing creek. A good weekend to get out!
Photos are here:
Overnight on the Ouachita Trail - OK - 041208 - 041308 pictures from hiking & backpacking photos on webshots
About a month earlier I headed east and spend a few days in Daingerfield, Atlanta and Tyler state parks. The trees were just starting to bloom and the trails were short but sweet. Too bad we don't have places like this closer to Dallas!
Photos are here:
Pineywoods of Northeast Texas - 031508 - 031608 pictures from texas photos on webshots