Actually, the Castiglione-Louvre area has several interesting stores. Serge Lutens is a must - it has the exclusives. It's in Palais Royal next to the Louvre. Parfums de Rosine is in the same square and one of the Nicolai just outside of it. From there, if you walk 5 min west on rue Faubourg St Honore, you get to the intersection with rue Castiglione, where you'll find, apart from the excellent Jovoy mentioned above, a Guerlain store, an Annick Goutal, the Patou store, and the (Paris exclusive and obscenely expensive) Jar. All on the same two blocks of rue Castiglione.