Sorry for the short review - didn't want to bore you! here a few more of our adventures.
7 days in Buenos Aires - for us, this was just the right amount of time to get the feel of the city. The early April weather was perfect. We stayed in Recoleta which was very convenient for walking to restaurants, the Cemetary and the many beautiful parks. Our favorite places were the Eva Peron Museum, the zoo, Japanese Gardens, and the fine arts museum. We aren't fans of modern art and the Malba museum was not our cup of tea. don't miss the Ateneo bookstore and coffee shop which was once a theater. Stunning!
I would recommend staying in an apart-hotel if you are staying more that a few days. We like a big breakfast and an early dinner, and both are hard to find in Buenos Aires. Our apartment in the Poetry Building gave us a lot of flexibility - even the best restaurants can be tiresome when you eat out 3x /day.
The architecture of Buenos Aires is beautiful - very European, lots of tree lined blvds.
Regarding money, most places took dollars. The official rate was about 5 pesos/dollar and the "unofficial" rate was about 8 pesos/dollar. We heard of 2 recent instances where tourists had been given counterfeit pesos, so we were careful. In small restaurants and shops we were given 7.5 pesos if we used dollars. We would try to pay for small purchases with a $50 or $100 bill and get our change in pesos at this higher rate. Please note that credit card purchases are at the official rate.
We were cautioned repeatedly about safety issues but we never had a problem and we never felt threatened. Of course we didn't wear jewelry or expensive watches. Common sense is all you need, just like traveling anywhere in the world.
The Salta region was arid and beautiful - a little like New Mexico and Arizona. We used a guide/driver but no reason you couldn't rent a car and explore on your own. We followed the Ruta de Vino and the scenery was incredible. We are not big wine aficionados, but this area has some high altitude vineyards that are fun to visit. We liked the wine museum in Cachi.
Iguazu Falls is certainly worth a visit. We had a tour company take us to and from the park, but you don't need a guide while you are there. The Fortin restaurant in the park is excellent. We didn't find the town of Iguazu very interesting, just lots of shops. However we ate at a very small place called Mi Mamma - exceptional homemade pastas! Not much atmosphere but great food.
We hope to go back to Argentina and explore the lake region. It's a long journey and an expensive flight, but at least our $160 Reciprocity Fee is good for 10 years!