Marty-
I live in Atlanta, but am in Dallas 3-4 times a year and there are a few places I love to hit when I'm there. Nick's card shop is one and another is Pie314 Pizza over in Carrollton.
Nick's used to have a nice selection of t206 and other tobacco cards, but they apparently sold a lot of those cards to one collector a couple years ago. Still a neat shop to go in and look around.
One of my best friends lives a few miles away in Carrollton and Pie314 is her pizza place of choice. I love it too - great low-key atmosphere and great pie!
http://www.pie314everydayeatery.com