The Costes brothers, of the too-cool Costes hotel, are perpetually in the forefront of whatever's trendy in town. Their brasserie near the Arc de Triomphe is a handy way to sample their cheeky flair, since it's open daily, serves nonstop, and has knockout over-the-top Napoléon III decor dreamed up by superstar designer Jacques Garcia -- black-lacquered tables, leopard upholstery, Bordeaux velvet, and a carefully tousled clientele picking at sea bass carpaccio, club sandwiches, tandoori chicken skewers, or waffles. Métro: Charles-de-Gaulle-Étoile.