Route suggestions, Dallas to AZ, say Phoenix

[Mrs. CountryGuy]

As some of you know, Al and I are on the road, slowly making our way from SE Michigan to Arizona. (If you are not aware, you can catch some of our antics on the blog, see my sig line, Reflections From the Fence.)

Next stop OK City, then Dallas/Fort Worth.

IF you were driving from Dallas/Fort Worth heading to Arizona, which route would you take, and can you suggest places to stop/camp about 250 miles apart, give or take 50.

What about HAVE to stops, for example can we get into Carlsbad Caverns area at this time of the year??

All suggestions gladly accepted and considered.

Thanks.