Six Senses retreats have a tendency to show up in the world’s most remote destinations—the mountains of Bhutan, the deserts of Saudi Arabia, or the beaches of the Seychelles, for instance—where majestic natural landscapes are as intrinsic to the healing experience as a menu of sound baths, cryotherapy, and acupuncture. Trading the tropics for the heart of London may seem like an unlikely backdrop for the brand’s 27th opening, but there’s also something to be said for arriving at the Six Senses London without a multi-leg, multi-day journey that requires, say, a wellness retreat to recover from. It’s easy to forget you’re in one of the world’s busiest cities when you enter a lush lobby brimming with more than 1,000 plants, and the 109 rooms, with bleached-wood floors, sage and blue accents, cloudlike beds, and fixtures that are a nod to the building’s Art Deco heritage, manage to deftly block out the tourist hordes of Notting Hill not far away, making for a surprisingly soft landing for an urban retreat.…