For your US account, NW can get you to Shanghai and HKG (take the train or something else from there to Guangdong). You earn US miles for NW trans-Pacific flights but they're not Q-miles (if it matters).

For AA miles, there is that CX offer but you will have to go on another carrier from HKG to either mainland destination. Alternatively, you can fly on JL (more U.S. gateways) via NRT, or OZ via SEL. JL and OZ flights earn miles but not q- or elite miles on AA.