Yeah the Big Texan is a tourist trap, they do have some alright micro-brew there. If you want to try some of the best hamburgers in the world try Coyote Bluff. Go south on Grand off I-40 look back to your east after the Walmart. Its a little hole in the wall place so keep a sharp eye, if you pass the toot n totum you've gone too far.
I second the recommendation on Coyote Bluff. When I lived in Amarillo, I ate at this place weekly. Still eat there every time I drive through Amarillo. For good Mexican food, try Tacos Garcia. Avoid the Big Texan. Ate there once, and never went back. Locals avoid it like the plague.