Jarrett, if you're already in Waxahachie, just drive up and check it out. Ride around White Rock Lake, up White Rock Creek, etc. Go ride in Plano, Richardson, wherever.

I think in general, you won't find good places to do reasonably long fast rides on trails. It is a 10 mile loop around White Rock Lake. That part is reasonably fast, if you don't mind riding the same 10 miles over and over. And on about half of it, the faster riders are all on the road, not the trail. White Rock Creek trail tends to be narrower and bumpier, and you can ride up it at 16 mph, but I would rank it lower in desirability than a lot of the suburban roads. Santa Fe Trail has a lot of road crossings, and not really a good part of town.
Plano has extensive bike trails, but they tend to have grade crossings at streets, so you ride a block and wait for traffic, ride a block and wait for traffic. Fine for taking the kids for a bike ride, lousy for getting a good workout.
Richardson has some on-street bike lanes. Basically, they're all on streets that don't need bike lanes. And some of them are combined bike/parking lanes, so you can't actually ride a bike in them due to parked cars. So zero value to most riders.
Some of the Trinity Trails are gravel, some are paved, so you have to know which is which.