I drove from Dallas to L.A. in the 70's and thought it was "easy" except for the mind-numbing boredom.
If you take I-40 instead of going through Dallas you'll hit some of the old Route 66 ("You see Amarillo - Gallup, New Mexico - Flagstaff, Arizona - Don't forget Winona - Kingman, Barstow, San Bernardino") which might be more interesting. I can think of side trips to the Meteor Crater, the Grand Canyon, and Laughlin, Nevada. Laughlin is a small casino town on the Colorado River near the southern tip of Nevada, about 25 miles off of I-40 near Needles, CA. It has some name brand casinos such as Harrah's, Golden Nugget, and Flamingo, and is known for rock-bottom hotel prices (about $30 a night at Harrah's, my favorite). And that's for a hotel on the river. Great buffets there too. But I don't know if I-40 is out of your way vs going through Dallas.