Considering this ride as a captioning service fund raiser.  I work as a captioner for Lovers Lane United Methodist Church in Dallas.  Anyone know anyone whose done this?  I am trying to avoid the neighborhoods as much as possible.  I am a highly experienced service road rider, and prefer a combination of those and straight, smooth secondary roads.

You may want to check out Lone Star Randonneurs (http://www.lonestarrandon.org/) as well as FWBA (too lazy to find their link), they have routes that will get you close.  Also, there is at least one route on Bikely (http://www.bikely.com/maps/bike-path/SXSFixed).
 
I've ridden LSRs route from Arlington to Wace, but none of the others.
 
Hope this helps

I rode US 77 and FM 308 to Waco, about 85 miles. I was riding to La Grange so I don't have a tested route from Waco to Austin.

Thanks for the responses!
Still going over courses, and I'll be looking at the experiences of X-country trekkers, (especially by trike), on crazyguyonabike.com/
Summer this year has been so full of riding that feel a difference in my base conditioning, even after several days of not riding due to work or weather.  Planning to commute to keep it all up, a max. of 40 miles, McKinney to Irving.  Starting light, then increasing the distance and reducing all the neighborhood twists and turns that Mr. Garmin wants to give me.