There is in fact no road that accesses Aguas Calientes from Cusco, so using a bus for the whole journey will not be a possibility. The trains are your best guess! We booked entire working day sacred valley tour with Cusco Local Good friend and our practical experience was wonderful. https://machu-picchu-tours94825.humor-blog.com/26338731/a-review-of-machu-picchu-hiking-tours-from-cusco