What are the most interesting places to visit in Texas on a road trip through the state?

The Texas Hill Country should definitely be on your list. This is a unique ecological area just north of San Antonio and West of Austin.  The best time to go is between March and April when the wild flowers are in full bloom. There are lots of funky, historic little towns, such as Blanco, Blanco State Park  http://www.tpwd.state.tx.us/spdest/findadest/parks/blanco/ Johnson City where the LBJ National Historic Park is located  http://www.nps.gov/lyjo/planyourvisit/directions.htm Stonewall where you can buy wild flower seeds harvested at Wildseed Farms http://www.wildseedfarms.com/meadows.html Fredericksburg home to Enchanted Rock State Natural Area... http://www.tpwd.state.tx.us/spdest/findadest/parks/enchanted_rock/ a charming downtown shopping area And the the National Museum of the Pacific War http://www.pacificwarmuseum.org/index.asp This area is also known for its peaches!!  Find out about the peaches here http://www.texaspeaches.com/

I once went on a road trip from Louisiana to California and back, crossing the widest part of Texas twice, and I absolutely loved driving there. I was on a misanthrope getaway, so I'm might be biased to say this, but the empty, flat and barren landscape in Interstate 10 was comforting and beautiful. Aside from just driving around, I recommend going to Big Bend National Park, Marfa and Study Butte-Terlingua, which are all around the same area. Big Bend National Park is on the border with Mexico, which I found quite interesting (Mexico is just across Rio Grande, which can get pretty narrow in some places). Study Butte-Terlingua is a very small village in the middle of nowhere. Some scenes from Paris, Texas, the Wim Wenders movie, were shot there, if you're into films. Marfa is where the "alien" lights appear every night. I was travelling by myself and the viewing platform is in an isolated place by the road, so I skipped the activity, by both fear of aliens and perverts. Some pictures of my trip in Big Bend National Park: Hiking: Hot springs by the Rio Grande river: Views of Sierra del Carmen in Mexico: US (left) and Mexico (right): Siesta in Boquillas village in Mexico:

if you're out west texas way, marfa is fun if you're into art. once a year the chianti (?whatever it is called) has an open house and all the galleries are open late and it's quite festive. stay in the hotel where the movie stars stayed when they filmed giant many moons ago. also out west is big bend national park, lovely hotel in the park to stay at, all levels of hiking around the park. and out that way is the mcdonald observatory, time it for one of the monthly "star parties" and you're in for a good time.   both fort worth & houston have museum quarters with impressive collections.   lots of lakes in central and east texas if that's your thing.   austin is a brilliant city to live in, visitors seem to like the special events throughout the year -- take your pick, acl festival and longhorn football in fall; austin marathon in feb; sxsw in spring; bluebonnets in central texas in spring; unbelievable heat and humidity in summer make the natural swimming holes around central texas and in austin a treat.   massive quantities of good food everywhere!

Having lived in Texas for 40+ years, here the most fun places, especially if you have kids traveling with you: Galveston Island: Saddle up yer horses (kiddos) and head to the beach!“Galveston is home to many attractions including 32 miles of beautiful beaches, splendid restaurants, top resort hotels, downtown shopping, art galleries, IMAX 3D Theater, Discovery Museum, Ridefilm Theater and Aquarium Pyramid.” Schlitterbahn Waterpark, New Braunfels: Pony on up to the best water slides in town and let go! “40+ rides including 17 water slides, family wave pool, three uphill water coasters, nine tube chutes, five swimming pools, five hot tubs, seven children’s water playgrounds, plus water and sand volleyball courts.” Houston Space Center: Before you go bonkers and launch your kids out into space, take ‘em on a field trip! “An extremely big glitzy building full of magnetism for kids — motion simulators, theaters by means of heavy-duty sound and seat motions, entertainment areas for little children and a lot more activities particularly for kids to be entertained.” The River Walk: Teach your children well! Like how to enjoy both history and outdoor scenery at the San Antonio River Walk. “The River Walk is a large place to learn extra on the subject of the history of San Antonio. It winds from side to side the old downtown region and a lot of noted historic sites.” Dallas World Aquarium: Tired of filling up the ‘ole baby pool? Take your little fishes to see underwater creatures in their own “pools.”  “The entire facility shows species as of five continents, three oceans, 14 countries, and numerous oceans and waterways.” Than Nguyen, http://www.texastreats.com/

I recommend Big Bend National Park if you like wide open spaces and wildlife, particularly birds.  If you are photographer it's a "must see" during migration time.