The MetroPCS Dallas White Rock Marathon route is still not confirmed, but the the Official Website www.RunTheRock.com does have a good estimation graphic of the route. I went ahead and tried to take it a step further and map it with MapMyRun.
Click here for my estimate based on their estimate: Unofficial Route map
I'm looking forward to the route and noticed that it has a couple of good inclines over the course of the 26.2 miles. Click the image below for a larger representation of what we have to look forward to.