We have done tons of walking at very high altitude, 11,000+ feet, and it's freezing cold (for us) but there has not been any significant grumbling.
We met a lady the other day on one of the tours and asked her if her hotel had heating, as our apartment doesn't. (You have to muster up all your courage just to go to the bathroom.) She said she wasn't sure if there was heat or not in her hotel and added, "Why would you need it?". She's from London.
This is really an amazing place to visit. The natural landscapes are amazing. We went through the Sacred Valley yesterday, a long, narrow valley boxed in by steep mountains on both sides and occasional towering peaks, some permanently covered in snow. Blending in in a very organic way, ancient Incan agricultural terraces and ruined cities. It's also fascinating to think that the rushing rivers draining to the east feed into the Amazon jungle. We are just at the edge between the Andes altiplano and the Amazon rainforest. Next week we are going to Machu Picchu, which I think actually lies within the rainforest.
We went to a village yesterday where we were shown how traditional weaving and dying is done. All the Quechua-speaking ladies were dressed in their traditional garb (but not just for the tourists). One of them had actually learned enough English to explain everything to us in English. (Unfortunately, the tour was not in Spanish.) She had a really cute accent, and even made jokes. It was amazing to see the variety of colors they can extract from different plants and the cochineal insect. They showed us how pure cochineal gives a black color, but when mixed with lemon juice it produces an orange color.
I also learned in a private discussion with our tour guide, that all those hand-made alpaca sweaters us tourists love to buy are not really alpaca wool. She said a pure alpaca sweater would cost about $100, which is why most Peruvians don't wear it. If it's "baby alpaca" (first cut), double the price The best quality wool is from the vicuña, which is what the Incan emperors used. These days a sweater made of this type of wool would cost upwards of $500! The guide also told me that cochineal is extremely expensive and is not used for dying any ordinary garments.