Both times I have been to Trex I have seen families there. The riding is very flowy (1 way on a couple of trails) with easy climbs back up. There isn't a ton of trails and you'll likely be repeating them several times. My normal route is to climb Brian's trail from the upper parking lot to the trail sign under the tree near the top follow the double track to upper, middle and lower Half Pipe then go to the connector trail that leads to a new trail over near where Kill Dozer used to be, do that, then climb back up the return trail to a connector trail between upper and middle Half Pipe that leads to the Brian's trail climb. From there, follow the double track to Broken Arrow, descend that to the intersection of the Fireman's trail. Fireman's trail eventually leads to Game Preserve road where you'll make a left and climb up a double track, back to the trail sign and tree at the top of Brian's trail. I'll usually do another lap of the route outlined above. There's a good map on Trailforks for reference.