South America has a crazy mix of landscapes, so it depends on what you like, but some standouts are Machu Picchu in Peru for the history and views, Patagonia (Chile/Argentina) for unreal mountains and trekking, Rio de Janeiro for beaches and city vibe, and Iguazu Falls on the Brazil–Argentina border, which honestly blew me away more than I expected. If you’re into culture, places like Cusco or Buenos Aires are great to just walk around and soak it in. I’d personally start with Peru and Brazil if it’s your first trip.