To do a round trip of all of Texas would involve over 30 hours of driving, so basically you would not do anything except drive 8 hours a day for four days. So breaking it up into a couple of different 4 day sections, I come up with Tour 1 - West Texas -Lubbock to Carlsbad (New Mexico) on the way to El Paso and then go to Big Bend National Park to San Angelo on the way back to Lubbock (19 hours of driving) Tour 2 - North Texas - Lubbock to Fort Worth and Dallas and then up to Amarillo and back to Dallas (12 hours) Tour 3 - South Texas - Lubbock to San Antonio to Corpus Christi to LaredoMidlandand back to Lubbock. (19 hours) Tour 4 - East Texas - Lubbock to Austin to Houston to Waco and back to Lubbock (18 Hours)
Claire order this: https://www.traveltexas.com/ Organized by region. Local details of all kinds: museums, natural wonders, parks, festivals, tourist meccas, small town stuff that is cool. Don't plan any travel in Texas without it.