There is little to suggest that the TriBeCa MedSpa in Manhattan is a medical facility, at least in the traditional sense. In the waiting area, called the Tranquillity Room, a waterfall cascades down one wall. A client may have a pedicure or facial before entering a softly lighted space where a plastic surgeon performs laser Fraxel treatment or some other minimally invasive procedure that would cost twice as much in a harried doctor’s office.