I went in the second half of April 2003, and it was absolutely beautiful and not crowded at all. Did the two day hike to get there, and wish I had done the four day hike. It was the experience of a lifetime. It only rained one morning, and I was in Peru for 12 days. Also hit Cusco, Lima, Ariquipa and the Colca Canyon. Try to see the Nasca lines if you get a chance.