I know I've read the answer to my questions over the past 6 months, but I can't seem to phrase the right search to find it.

On Thursday morning I have about four hours between arriving in LHR on AA (cheap ticket, upgraded to business with eVIP) and leaving for Hong Kong on CX at 12:45 PM (a DONE4).

As an AA EXP I believe I can use any of the OW lounges - where should I head? The obvious answer would seem CX's - but the obvious answer is sometimes not the best answer.

And more generally, since I hold a Qantas Club card, are there times when I will do better showing that rather than my EXP card? Right now I only ever break out the Qantas Club card in the US on domestic trips.

Thanks in advance for any insight.