Just as an update for anyone flying via DFW, I visited the QF lounge in Terminal D. The lady guarding the desk in front of the lounges at first said it was "only for those catching the QF flight from DFW - SYD", but then another employee set her straight and explained to her that as a QF WP I was entitled to visit.
As far as US lounges go, it was pretty decent. Free beer wine and spirits, some edible hot food, sandwiches (each featuring Vegemite - like ham, cream cheese and Vegemite!?) drinks, plenty of space and views of the tarmac. Free wifi. Cant recall if there were showers.
I didn't take a look at the Admirals Club, as the lady who actually knew something about lounge access rules told me not to bother as the QF lounge was much better.
The lounge was located near gate 20.