I can't help regarding the planes you will be on. I flew business from SFO to PEK so we were on the 747-400 combi. As far as the lounge in Shanghai, it's nothing to write home about. The lounge we used was upstairs overlooking the concourse. The seats were nice compared to the rest of the terminal, recliners if I remember correctly, the attendants were friendly. There was the usual snack treats, coolers with drinks, cakes, etc. I know that I would not want to spend 7 hours there.

Did not go to the lounge in PEK because layover was only an hour.