I would also take 90 to Del Rio. And from there, dip down to Big Bend National Park. If you have your bike (and even if you don't) drive from Terlingua west along the border (route 170) for some of the most beautiful landscapes in Texas. In Terlingua, stay at BJs RV Park - you will not find friendlier hosts anywhere.
From there you can go north and check out Marfa and the other small towns on your way to Carlsbad. Fort Davis is also an interesting stop to wander or stretch your legs.
In New Mexico, I can recommend City of Rocks state park, particularly if you can dry camp. The camp sites are among the rock formations.
In Arizona, if you have the time, check out the Dragoon Mountains. Then head down to Bisbee, a really cool town.
2015 Jeep Willys Wrangler
2014 Fleetwood Bounder 33C
States camped: all but Hawaii
more than 1700 days on the road