Since NW replaced 744 by 757 or DC10, fares to PEK have been ridiculously high. Meanwhile, UA has ORD-PEK and SFO-PEK(in June) daily so most people to PEK will fly UA instead of NW (unless they want to fly other Asian airlines).
Another solution is to do an open jaw: DTW-PEK, PVG-DTW. If you have time, then you can visit Shanghai. Since PVG-NRT uses a 744, M fares are available for most of summer.
On a separate note, I am going to write to NW about upgradable fares to China. While M fare can be upgraded to all other Asian countries, however to China you need B fare, a difference of $600. Do NW marketing guys think people going to or from China are richer?
