1. The buses in Peru take security more seriously than their neighboring countries. In fact, multiple times we had to show passports, be searched for weapons, have a photo taken, and a video of where we sat on the bus. It was weird.
2. Northern Peru is cheaper, but I didn’t particularly enjoy it that much. It was worth the trip we made, but we ended up leaving the country about four days earlier to get to Ecuador. Everyone has their personal tastes, but the desert and lack of development in northern Peru made it not as welcoming as we had anticipated.
3. Expect changes in temperature, from the altitude of Cusco and Puno to the desert in Arequipe and Ica, to the foggy Lima.
4. We did the overnight stay on Amantani island, and though it was more expensive, I think the trip wouldn’t have been worthwhile unless we made that little bit of extra effort to get to know a local family and see what real local life is like.
5. Bring lots of cash or, at least, really try to limit your ATM withdrawals. Fees were around six or seven dollars a use, especially in Cusco (Colombia, however, is even worse).
6. Just as a warning: Cusco is a different world, particularly for backpackers who have spent most of their time in local or less-developed areas. Cusco is all about catering to the rich American/British tourists that come through, from highly expensive Coach stores to 4- or 5-star hotels. Budget options can be found, but it was some of the strangest culture shock I’ve ever experienced.
7. Machu Picchu really is worth the small fortune required of you. And all those people commenting on the Lonely Planet threads? When they say get on the first bus at 5:30 in Agua Calientes to see Machu Picchu before hordes of tourists descend on it, do it. It’s so worth it, even though we had to wake up at 3:50 am. So worth it.
8. We found the cheapest deals on tours (especially in Puno) to be at the tour offices downtown. Don’t pay too much attention to the online prices. I thought we would have to pay around 80 USD per person to do the Amantani/Taquile/Floating islands overnight tour, but we booked through the hostel for about 45 USD apiece. Later we discovered that if we had gone straight to a tour office, it would have been about 35 USD a person.