The SPG is definitely not a good choice.

Your calculation for the SPG is a bit off as the 2.7% FTF is purely a fee and not part of your original spending.

Using your numbers, 16000 points for a night that cost 1500 CNY ( ~ 245 USD ) , that's a rewards rate at 1.53 cents (US) per USD spend, and the 2.7% FTF is more than double your rewards rate. So that's not a option that you should consider at all.

AMEX Plat also isn't a good option given the $450 annual fee unless you can really use the benefits like lounge access or the hotel perks with FHR.

I would suggest the Discover IT card. It's a 1% Cashback with rotating 5% category, but it has no annual fee, no foreign transaction fees, no DCC, and it runs on the UnionPay network in China, so its acceptance will be much better than AMEX ( or even Visa / MC for that matter )

If the stores that you visits doesn't force DCC, then CapitalOne QuickSilver Visa offers 1.5% Cashback, no annual fee, no FTF