http://www.tourdenorway.com/   Clifton, Tx, a bit southwest of Hillsboro, about a 2 hour drive.
 
This is only their 2nd year but it sounds like a great ride already.  They added a 60-mile route this year (20, 40, 60 and 80).  Here's the 80-mile route -- there's a 2-mile bit of nastiness just before Meridian, but it's apparently only 4% or so, not much worse than the Mesquite climb out by the racetrack....  but it IS 2 miles...  but it's followed by a 3/4 mile 5% downhill!!!   Watch out, 50mph barrier!!!!   And it looks like the last ~15 miles are mostly downhill...
 
http://ridewithgps.com/routes/2471534
 

I did this last year - was a good ride. Looks like I'll be there again tomorrow (Saturday) for the ride!