I present my ML club card at all non-AC lounges. There is almost always a line and the card plus BP speeds things up. As OP said above, not all *A lounges can read BP codes and non of the contract lounges I've used can.

I used it at the ANA in HND, the Dan in TLV and each time I go through the UC in SFO. Interestingly, the Air NZ lounge (still at LAX T2) seems to have better tech. Their bar code reader had no problem with my BP and I looked on the screen and saw how it logs the pax info. Very interesting. (Of course, they are moving to TBIT.)