My husband is from Peru. We went to Machu Pichu two years ago and it was fabulous. I really liked Cuzcu. Its such a great old city. We got very sick when we got there, as did most of the people getting off the plane. A few even threw up right on the floor of the airport. Its really bad. When you check into a hotel, they give you cocoa tea. It helps a little, but not much. I don't know if I would have been able to take the train up to Machu Pichu the same day we arrived in Cuzcu. For people who don't know, you can walk into any pharmacy and get any perscription you want in Peru. They have medicine there for the altitude sickness.
Anyway, the trip up to Machu Pichu on the train is very long. About 3 hours. It is a beautiful ride. The trip back takes longer, for some reason. They no longer have the helicopter ride going up there. We were planning on doing that. They've canceled them, due to the vibrations damaging the moutains.