Remede Spa, St. Regis Abu Dhabi, United Arab Emirates, stregisabudhabi.com In the United Arab Emirates—home to some of the most gigantic oil fortunes on earth—bigger is always better. This enormous spa, in the opulent new St. Regis hotel overlooking the Arabian Gulf, features treatment suites larger than typical Manhattan studio apartments, complete with private showers and water views through the floor-to-ceiling windows. The most copious local ingredient in this part of the world is desert sand, which is mixed with argan oil and sea salt in a body scrub. And though the list of services is lengthy, one thing you won’t find is a couples massage: In keeping with local customs, the establishment is ladies-only. Men have their own spa in a separate space.