I lived in Flower Mound, Farmers Branch and Denton. There was a huge difference using the rabbit ears/ clip-on bowtie on my 1967 Philco 19" color set, 30 years ago. The first two places had very good signal, but Denton had lousy.
I did get KXII in Denton but the DFW channels were not good at all, and a medium sized attic antenna probably would have been adequate. I expect digital would be tough as well.
If you are over 35 miles away from DFW's transmitters in Grand Prarie, there is a drop-off point where no set-top antenna would be acceptable.
As Don says above, this website
http://transition.fcc.gov/mb/engineering/maps/ is a good start. I would try a 4 bay bowtie, move it around for hot spots and use a Channel Master 7777 preamp if you dont get all the channels.