Junction, Fredricksburg, and Kerrville, Texas are located near I-10 and US 190/290 and are well worth a visit on your way east. Junction has one of our favorite Texas state campgrounds at South Llano River State Park. The very nice, tree-shaded campground has 30A electric and water plus a dump for $20/night. Fredricksburg is an old German town in the Texas Hill Country with many 19th-century stone buildings in the restored downtown. It was the hometown of Admiral Chester Nimitz, who commanded all the forces in the Central Pacific Theater during WWII, so has an interesting WWII Pacific Theater Museum. Kerrville is another German Hill Country town with a city-owned campground that is a former state park.
If you are going to Carlsbad Caverns, US 180/62 east of El Paso traverses some pretty dreary scenery--dry, dusty playas and barren hills--until you get to Guadalupe Mountains National Park. Although the scenery improves, the caverns make the trip worth the drive.