1. The Pantanal. A huge swamp. Jaguars, giant river otters, caiman, capybaras, and an amazing variety of birds and lizards. Probably the least well known great place for wildlife viewing anywhere.
2.Rural Guatemala. Really! OK, being more specific, Lago Atitlan, Tikal, Antigua, or pretty much anywhere in the countryside. Amazing sites, incredible cheap food, big fun.
3. Patagonia. We have only been to Chilean Patagonia, and it is an incredible pain the the butt to get there but wow, it is so worth it. In Torres del Paine park, you can hike to see glacial lakes and incredible peaks, and still stay indoors in refugios with indoor plumbing, hot water, and hot food.
4. Mexico City. Really it's impossible for me to pick one only place in Mexico and uninformative to simply list the whole country so let me apologize to Oaxaca, the Yucatan, and the states of Guerrero, Chiapas, and Baja Sur. Mexico City has the best food, museums, suburbs, and outlying attractions of anywhere in Latin America, if not the world. A great place to spend at least a couple of weeks.
5. Urubamba valley, Peru. This is where I want to retire! I think it may be the most beautiful spot on earth. It's also close to Cusco and Machu Picchu. Here's a pic: