As someone who has been living in China since 2006, here is my take on the CC situation.

- Any US credit cards will have some issues
- Cards will often be rejected on principal because "We don't accept foreign cards"
- Discover is most widely accepted as it is on same network as UnionPay EXCEPT
a) You will still receive the "We don't accept foreign cards" objection even if it does work
b) The card doesn't actually bear the UnionPay logo so the merchants won't necessarily believe your word or any piece of paper you hand them
- For Visa/MC be aware of DCC which can add 3% - 4% to the price

If you're not concerned about rewards/miles then best choice is to open a local bank account and use the bank card.