What’s couture all about? Big dresses, and satisfying clients. Giambattista Valli is good at both. Ladies in his lavish cocktail dresses say front row salivating over more of the same, in frothy feathers and florals, while he saved the massive tulle skirted humdingers for the end. Giamba – as his mates call him – is chucking a ball this evening at the Palais Garnier. I’m betting at least one of his fluffy finale frocks makes a grand entrance there.