The main attraction at Machu Picchu is the Incan ruins. Long story short, there really isn't much else going on; and well, given the draw of the ruins themselves, there really needn't be. A whole-day (or more) could easily be spent wandering through the ruins. You will want to have a guidebook that provides extensive coverage of the ruins themselves so that you will actually know what you are looking at as you hike through the area.

If you plan to spend a few days in Agua Caliente, there are a few other sites that you can experience if you happen to get a little overwhelmed by the ruins:

Mandor Waterfall is a 45-minute hike from the Machu Picchu Pueblo located off of the railway line. The hike offers an excellent trek through the forest, where you can experience Peruvian flora and fauna firsthand. Entrance to the waterfall is S./ 10.

Hot Springs -- after a long day at the ruins, you'll want to rewind at the hot springs located near to the ruins. The hot springs are located just a short walk from the main plaza. Entrance to the hot springs is also S./ 10.