First time doing this rally...  may not be the last!  Too bad it's a 5-hour drive from Dallas...
 
Excellent road surfaces the whole way, with the first and last 20 miles being nice and flat due to following the Arkansas River Trail (with the exception of crossing the two river bridges).  Tough climb sections from mile 30 through 45, but with some nice, scenic downhills - especially a screamer at mile 45..., followed by another flat ~20 miles, then the climbing gets ugly around mile 63, where you have to climb "Wye Mountain" -- essentially a mile of 6-12% uphill...  followed by another 6-7 miles of rollers and shorter climbs, when it finally goes back downhill... but you're not done with hills until you reach the River Trail again.
 
I severely underestimated this ride, thinking I might finish in 7 hours max -- it took almost 8.  I was climbing in absolute bottom granny gear (28/36) several times during the day...  Both the 100 mile and the 68 mile routes make you climb Wye Mountain...
 
Beautiful countryside, and smooth roads, and well organized.  Highly recommended, but get ready to climb!
 
My pics are on my Facebook page.
 
Paul