Argentina is a country that is so large that you have to be there a couple of times to see the best sights. Make sure you have ample of time and take some flights in between as distances are often way too far to go by car. Although Buenos Aires is naturally the first stop make sure you get to see Iguazú, one of the most impressive waterfalls in the world. Explore Mendoza, the wine country that saw tremendous growth in tourism over the last couple of years. You might want to rent a car and explore the Andes that provide the background.