The Champs-Elysées might be the Times Square of Paris, but the famous avenue just received a serious dose of chic from the newly renovated L’Institut Guerlain. The historic town house, which has been updated by the architect Peter Marino, has a bright and lively first floor devoted to cosmetics and skincare; a fragrance-focused second floor displaying archival scents dating back to the Napoleonic era, as well as a bottle-monogramming bar; and a third-floor spa that offers a wide range of facials and massages. If you really want to do it up, go for the aptly named Voluptuous Experience ($1,060), a five-hour indulgence that includes a body massage, hand and foot treatments, and a deep-cleansing facial—with a three-course lunch. You might even want to stay for dinner. Chef Guy Martin (of Le Grand Véfour fame) turns out an intoxicating farm-to-table menu at Le 68 Guy Martin, on the ground floor. No spa robes allowed.