SFO to SZX via PVG and WUH? Gosh, that's a long way out for transit.
Why not do SFO-HKG? Too expensive? Or at least SFO-PVG-SZX?
Over night stay in most of in-land domestic Chinese airport is no fun, I will avoid as much as I can. PVG handling should be fine, and even stay overnight is easy. Int'l to Domestic in PVG only involves walking, sometimes a lot of walking, but not really difficult to navigate.
I would choose MU over KE every time, due to poor safety record of Korean airlines, KE is even worse than OZ.