exchange your cash to American Express Traveler Check at local bank in the states. 4% commssion, can be cash out at any Bank of China branch. American issued creidt cards may refer to your statement for cash APR %. and now they also will charge 3% oversea processing fees.
all the credit cards can be used in China now, average processing charge 3% to 4%, the best way is to call your bank, and credit card issuer. have fun there, man.