Wellness travel is booming, and hotels large and small are wooing guests with state-of-the-art spas, fitness centers, classes and retreats. Here are some of the latest properties, where wellness goes beyond facials and yoga to sleep tracking, local rituals and even medical services like getting an echocardiogram. Whether you want to sink into a hot spring in Japan or receive a massageon a train as it rolls toward a Malaysian jungle, these getaways strive to transport you in more ways than one.