In October, 2015 I volunteered with 7 other members of my company in Cusco. We participated in an after school program for underprivileged children in the mountains outside of the city. They did a great job with orientation, preparing us the experience, and making sure we were comfortable and taking full advantage of all the various opportunities (including learning Spanish) along the way.
At the end of the week, they put together all the plans and tickets for us to go to Machu Picchu, where we also climbed Huayna Picchu mountain, which has limited tickets available. It was a smooth and awesome end to the trip.
The professionalism and effort the staff took was immense and resulted in a fantastic volunteer experience that I will carry with me the rest of my life. I would highly recommend it to anyone interested in taking advantage of it.