For BA lounges in the US, be warned that being entitled to access according to the rules is no guarantee of actually being admitted. BA is notoriously stingy about granting access to oneworld elites flying on other airlines at US airports. I haven't tried at IAH, but I have been denied access multiple times at ORD, PHL, and IAD. They will claim capacity issues even though the lounge behind them is totally empty. So please don't count on seeing the inside of this lounge because of having a QR or AA boarding pass.