Whatever you do, don't skip Western Arkansas. Eastern part is flat and many dirt roads have been covered with deep fresh gravel by oil companies.
The west is a different story. It takes you through the beautiful Ozarks - the location of out 9th Annual Squeal Like a Pig Rally (see here
As far as Oklahoma goes, well I live here and I haven't done it
It's flat and dirty. If it rains it's slicker than snot and if it's hot and dry it's hotter than hell. NM is so short I wouldn't skip any of it. Eastern Colorado is pretty boring and I would definitely try to find some shortcuts. Once you hit the Rockies the real fun begins.
I have only done a short part of Utah, but I want to finish the Western portion of TAT real bad.
That's just my 2 cents. Good luck with your trip.