As others have said, there is no chance of entering any Air China lounge on arrival.
Assuming that your girlfriend is arriving in T3, then you don't really need to arrange a meeting point since there is only one place for here to exit from. Not sure there's anything especially captivating in T3 landside. If your hotel is near enough to the subway, I'd almost be tempted to head out, check in and then head back to the airport to pick up the girlfriend. She would still probably need to have her documents checked by the hotel when she arrives though.