9. Take a suitcase if you are not on a year's long trip! I originally thought a backpack was the best option but in the end, we took both a backpack and a suitcase. The backpack was not ideal, as it was hard to lock up, customs seem to like rummaging through it! Also it is too bulky and does not hold as much as you would like it to. I thought Cusco was predominately a backpackers world but it is not. A suit case will not look out of place.
10. Altitude sickness. One symptom is waking up at 3 or 4 in the morning with a stabbing headache!! I didn't know this until I have experienced it and swapped stories with fellow travelers. Just take some pain killers for headaches. Also since we went slow, we didn't experience altitude sickness on the inca trail but everyone in our group did!
Enjoy Peru, it was truly better than I expected, which makes our next destination a hard act to follow!