What was your big culture shock when visiting South America?
More than 2x USA and 13 countries, so size distance to travel, you need to plan to be cost effective.
Diversity, deserts, volcanos reflecting in lakes, ice blocks falling into the ocean.
Some crazy big cities
Iguassu water falls, over 3km long
Machu Picchu, 3 day Inca trail hike
Lapaz city and a 2 hour bus ride to 16,000 feet, simple skiing can done.
The possibility to find "Eternal Spring" places to live.
The importance of knowing some Spanish
I haven't been to South America; the closest I've been is Panamá, in Central America.
I have been to Mexico several times, where I was surprised by the sometime lackadaisical food sanitation. From my seat in a bus stuck in traffic, I once saw a pickup truck carrying a load of raw chicken in the hot sun with no ice or other refrigeration. In markets when I asked about different spice mixtures (mole) sold in bulk, I was told to just reach in and try them.