I had a couple of much lighter weight thoughts -- also others have made the obvious points about MRU if you are in Europe (as compared to being at SFO, where I just couldn't make that make sense).

Assuming you are starting at NRT... for the North America segments you could consider at least SFO-SAN-LAX; typically that can be done for the cost of just a couple of hours.

LAX-NRT could be flown LAX-HKG-NRT for another few hours at the other end.

One other option depending upon your plans is TPE as a start point. Slightly more than NRT, but it gives you more flexibility on your return if you want to build miles. Originating at NRT has the slight disadvantage that you cannot use JL to return to Asia unless you want to indeed end the journey then (since you will have touched "home soil").

I am quite interested in the DOH option myself now...it sounds cheaper than TPE.

Steve