You might want to take a look at Slipstream Aviation at Dallas Exec. I knew the owner several years ago, and although we haven't talked in 3+ years, I can tell you he was a really terrific guy and one heck of a great aviator. IIRC, I signed him off for one of his CFI ratings... but I'd say he taught me more than I taught him whenever we flew together!
I heard through a friend that he started this flight school. I can't speak for the school itself, but if the owner is anything like I remember, he's likely upholding a high standard of quality and service.
Just thought I'd throw it out there - might be worth looking into.
Fly Slipstream Aviation - your source for flight training and airplane rental in Dallas Texas