I'd have to go with Peru ... Machu Picchu, and all.
It's a wonderful experience. Four-day, 44-km hike along the Inca Trail from Sacsayhuaman to Machu Picchu. On the morning of the fourth day you can watch the sunrise at Inti Punku ("door of the sun") over the ruins of Machu Picchu. Take clothes for all seasons. The floor is about 200 meters above sea level but there are passes over 4000 meters high, so in one day you'll switch from shorts and a wifebeater to jacket and gloves and back again. Lots of grueling ups and downs, made easier if you pick up a little packet of
lejía y coca to consume en route.