How about KA F to CX F: PEK-HKG-BOS, as a OW Sapphire?
KA's website says 2 x 32KG for first and business class pax, but 3 x 32KG for Marco Polo Diamond and Gold card holders. I've always found CX OW reciprocity to be very good, except for golf cart rides at HKG, will the Marco Polo "Gold" exemption (I presume Gold is OW Sapphire) apply in my case?