This whole post has some really good information. I do have a couple of nits to pick:
Rolling through East Texas will be Piney woods, swamps and oil towns, not a lot to see except for the trees, youll stop in Longview (rest stop) where pax catch the bus for Houston and La, then Marshall is the next stop but you cant get off there but they change crews and theres a restored depot that looks pretty Victorian.
Marshall is the first stop beyond Texarkana, they you get to Longview.
Dallas will be a rest stop, sometimes long, it's right downtown, yourea block from Dealy Plaza and the Book Depositiry museum, youll cross the rail trestle where you can look to the right where JFK was killed,
I would not call this a trestle. This is the "triple underpass" from the street perspective. It iis immediately past the station. If looking out the right side going southbound, the left hand street was the one Kennedy's motorcade was on. He was heading toward the underpass. The rather non-descript 4 or 5 story brick building that is about a block away from you and on the left side of the street is where Oswald was when he fired the shot.
A few other thoughts: All track on which the train runs is Union Pacific except Chicago to Joliet which is Candian National and Ft. Worth to Temple which is BNSF. Maximum speed limits, with numerous restrictions to lesser limits are 79 mph between Chicago and St. Louis, 60 mph between St. Louis and Poplar Bluff MO, 75 mph between Poplar Bluff and Ft. Worth, 79 mph between Ft. Worth and Temple, and 70 mph between Temple and Austin. Almost all is single track, except about 70 miles in Arkansas and Dallas to Ft. Worth.
Historical ownership of the railroad lines from last before current then backing up:
Chicago to St. Louis: Chicago Missouri and Western, Illinois Central, Gulf Mobile and Ohio, Chicago and Alton. line commonly referred to as the Alton Route.
St. Louis to Texarkana: Missouri Pacific, St. Louis, Iron Mountain and Southern, before MoPac, commonly called the Iron Mountain. Between Chicago and Poplar Bluff, the line is very hilly and crooked and carries little freight which uses another route.
Texarkana to Ft. Worth: Missouri Pacific, Texas and Pacific. The T&P had aspirations of being the second if not the first Transcontinental, but lost out to Southern Pacific west of El Paso.
Ft. Worth to Temple: Atchison, Topeka, and Santa Fe. usually simply called the Santa Fe. Thanks to a peculiarity of Texas law, the line was legally the Gulf, Colorado and Santa Fe for many years.
Temple to Taylor: Missouri Pacific, Missouri-Kansas-Texas, commonly called The Katy.
Taylor to Austin (and on to San Antonio): Missouri Pacific, International Great Northern. (international in this name refers to Mexico.)
Wish I was on the train too, probably won't be going again until October!!! 
