RE: fajita's - DFW- Blue Mesa Grill or Joe T Garcia's?
Sonny Bryan's should be skipped. Though, so far as I know, no great barbecue can be found in Dallas, one can definitely do much better than Sonny Bryan's. Check out some of the reports (with photos) at the DallasFood.org web site to get some better ideas. (You might also want to check out the "visitors' information guide" there.)
As for fajitas, I wouldn't do Blue Mesa or Joe T. Garcia's (which has great atmosphere, but mediocre food). I'd probably go for the "sunset fajitas" at Mia's. (The "sunset sauce" that comes with it is a potent chipotle queso.) Most fajitas in this town are pretty fungible. The best places, for that dish, are down in the Valley.
If you're going to be in Fort Worth, consider going to Lanny's Alta Cocina Mexicana. Lanny Lancarte is the young, talented son of the current operators of Joe T's. He's a CIA grad who's worked with Rick Bayless in Chicago and Diane Kennedy. His family wanted him to come back to Joe T. Garcia's, but he didn't want to do Tex-Mex. So they gave him free reign. He opened his restaurant-within-a-restaurant in a room at Garcia's a little over a year ago, doing upscale Nueva Cocina tasting menus. And, I tell you, he's doing fantastic work. His is definitely the best restaurant in Fort Worth (in any category) and is competitive with the top tier of fine dining establishments in Dallas. For a meal report from Lanny's, with photos, check out the following link: