I grew up in Dallas. I left at age 18 and have never gone back except for visits.
Having said that, Dallas is not the same place I left in 1985, so I think you will find some good places to eat there. When I visit my mom, we tend not to frequent hip new places, so I can't give you too many current recommendations. However, we've done the road trip a few times. (BTW, we've found the Memphis/Little Rock/Texarkana route preferable to the St. Louis/Joplin/Oklahoma route). Here's our highlights:
Lambert's Cafe I
Sikeston, MO
2305 E. Malone
Sikeston, MO 63801
573-471-4261
http://www.throwedrolls.com/
Lambert's is the home of throwed rolls. That's right -- they throw rolls at you. But in a nice way. This is good, down-home southern cooking. Sikeston is one exit (I think) north of where I57 ends at I55 in southern Missouri. So, instead of exiting from I57 to I55 south, take I55 north. It's a fun, kitschy, decent place to eat. Far and away better than chains.
Bryce's Cafeteria
2021 Mall Dr.
Exit 222 off I-30
Texarkana, TX 75503
http://www.roadfood.com/Reviews/Overview.aspx?RefID=290
Moving to Texas, you must learn the pleasures (and perils) of the cafeteria. Bryce's is probably the best in the world of the Texas cafeteria genre, especially now that the late great Highland Park Cafeteria is gone. Huge selection of great southern/Texan food at great prices. Be sure to time your trip for a visit. It's worth it.
The Mecca Restaurant
10422 Harry Hines Blvd
Dallas, TX
75220-4414
Phone: (214) 352-0051
Cross Street:
Walnut Hill Lane
Of all the old-school Dallas restaurants, this one is my favorite. Again, its Texas/southern home cooking -- chicken-fried steak, biscuits, gravy. It feels unchanged from when I was a little kid. When you are REALLY hungry for a huge-ass breakfast, head on over there. After you sit down in a booth, you would swear LBJ or Sam Rayburn could walk through the door, pressing the flesh and bellowing about how so-and-so is a real SOB.
The culinary warning about Dallas is that it is the home of many a terrible chain restauarant idea (it's the Brinker company home). There was a time when Chili's was a bar and grill on Greenville Ave. and a place to get a decent burger. Long ago.
Anyway, good luck to you, and please post some good Dallas finds here in the "Beyond Chicagoland" section. I can no doubt make use of them on my next visit.
LATE BREAKING UPDATE: Some word that the late, great Highland Park Cafeteria is taking over the Casa Linda Cafeteria (Buckner Blvd and Garland Rd in East Dallas). If that's true, try it out for me and let me know how it is!