AA has one of the most generous FF schemes around so im sure this is a factor.

And tbh, you kind of answered your own question....

""you have little option in DFW and north Chicago markets. If that is the case I understand""

There is not much choice i would assume for most people flying AA. And AA arn't all that bad btw. How many times have you flown AA dom F? I havn't flown it all that much but i find the service to be good, polite, helpfull and generally of the standard i would expect on a domestic F product. AA's Intl J and F is also a very good product. Not up to the standards of VS/BA/CX/QF/SQ etc, but for their main competition they easily match UA/DL/CO/NW and US in respective classes.

Also, if you are on an intl itin you get free drinks vouchers in the AC!

Chris