Trains
Tailored to visitors & relatively expensive
The train system was privatized in the 1990s, with the result being that it now is more for tourism than for public transportation. PeruRail and IncaTrail are both subsidiaries of the same company, which fixes prices quite high.
Trains from Cusco to both Machu Picchu and Puno are particularly designed for tourism and quite expensive. That said, if you love trains, this is a very fun day. Both the Vistadome train to Aguas Calientes and the train to Puno have professional dancers performing traditional Andean dances.