I am making my second trip to PVG next week using AA.
It is very hard to get seats on the AA PVG flight, at least in Business Class.
My alternative routing is BDL-DFW-KIX-PVG, using JL for the last leg. AA does not codeshare on this flight and, while you will earn AA miles, you will not earn status miles.
For the OP, since there really isn't a practical premium economy way to get there, I would reccomend AA from LAX to NRT and then JL to PVG.