In NRT, JAL is the best OW F lounge. En route NRT-ORD, in F, the "FT way", CCR in LHR T5 beats all others. To accumulate AA milage, as no access to T5 with AA T3 BP, go BA LHR-MEX, AA codeshare MX MEX-ORD, or for yet better milage AA MEX-MIA-ORD. BA LHR-YVR (BA F lounge) then YVR-ORD.

A little pain on time, lots of gain on lounges and miles. But you know the saying: No Pain, No Gain!