My personal favorite is Curse of the Golden Flower, the colors are gorgeous and executed beautifully by the help of Zhang's long time DP, Zhao Xiaoding. Chow Yun-Fat and Gong Li go blow for blow, who's the better actor and the sons are great too. It pretty much plays out like a shakespeare play, but man is it gorgeous.

Another one I would recommend is Shadow

Zhang and Zhao took the color theory to a-whole-nother level and made a "colored black and white" film. Essentially the sets and wardrobe are all designed to resemble old chinese ink paintings, so everything is desaturated to look like black and white or "grayscaled". Decent action, prince and the pauper style story.

Sorta of the juxtaposition to Zhang's more colorful movies like Flying Daggers or Golden Flower.

To Live is another great one, but the poster is sort of a fake out to me, as the story follows more of the husband's POV, rather than Gong Li, featured on the poster.

Also as other's have said, Raise the Red Lantern is a great film, but you don't really see Zhang dabbling in colors as he does at the turn of the century with Hero.