You won't appreciate the *G benefits until you lose it, and that's what I experienced in my last trip.

A little background: On May 6th I booked the following ticket with Lufthansa:
IAD-(LH)-FRA-(LH)-PEK on 06/01;
PEK-(CA)-FRA-(LH)-IAH-(UA)-AUS on 08/25.
Since I'm only a *S member, the free luggage allowance was only one piece, with the second piece charged at USD 70. Also, when I look up my reservation on United.com, it explicitly shows the second piece would be charged at USD 70 for both directions. (I know Lufthansa raised the fee to USD 100 for tickets purchased after June 1st, but that does not apply to my ticket anyway).

When I checked in for the outbound flight with Lufthansa at IAD, I was charged USD 70 for the second piece, which was correct. The fun began when I checked in at PEK with Air China for the return flight. Upon check-in, the Air China staff asked for USD 200 for the second piece. I was absolutely shocked! I argued with them that it should be USD 70, definitely not USD 200. But they said that they had dealt with many similar cases, and USD 200 was the correct amount. I did not give up, because I remember there is a US DOT regulation saying that for any itinerary touching US airports, (1) the baggage rule is determined by the first marketing carrier; (2) the outbound baggage fee applies for the whole itinerary. To verify, I called Lufthansa support desk. Much to my surprise, the agent told me that the DOT regulation applies to the free allowance only, and the excess bag fee is determined by the operating carrier, and hence I was subject to Air China's excess fee!

I suspect that what the agent told me was wrong, as it would be hard to imagine how to combine one airline's free allowance with another airline's excess fee. In my opinion, the correct rule could only be one of the following:

(1) The marketing carrier, Lufthansa's baggage policy applies. In this case I should be charged USD 70 for the second piece.

(2) The operating carrier, Air China's baggage policy applies. In this case, their free allowance between China and the US is two pieces, and I shall not be charged anything. By the way, Air China's excess fee for the third piece between CHina and the US is indeed USD 200, but I think it's unfair to apply the fee for the third piece towards my second piece.

What do you guys think? Thanks a lot!