I recommend Howell's Aircraft Services located at GPM (Grand Prairie Municipal). They have a bunch of pretty good instructors, and a REALLY good chief pilot named Dick Ehrler. He is an older wiser type of instructor, probably a real instructor that intends on doing it the rest of his life. I don't have any experience at Monarch in ADS (Addison), but they seem to be well run. Of course you can always go to American flyers, just like the earlier post says.