El Tuco is a great hostel. It's quiet, relaxing, clean and has everything you could expect or need. But the best thing about El Tuco is the owner/host Coco. Coco was endlessly helpful to my friends and I during our stay, with recommendations and directions for Cusco, advising us on medications for our freind who was suffering altitude sickness and helping us plan our Machu Pichu trek.
When we returned from our trek and had some issues with the tour company we had booked with (independent of El Tuco), Coco rang the tour agent and organised him to visit the hotel and then supported us in voicing our complaints and obtaining a partial refund... More than you could possibly ask for from a host.