How much cash to take to Beijing?

We are travelling as a family of 5 and intend to do a quite bit of shopping; suits for the hubby, clothes and shoes for me and the kids, and what ever else we fancy. We hear the Silk Markets are good. So do we need cash for the markets or should we take a combination of cash and travellers cheques? And do these popular tourist attractions accept credit cards? The NZ exchange rate is excellent at the moment so we thought we would capitalise on that and take quite a bit of cash, but don't know if that is wise. Your thoughts please?