Argentina

Please post a plan or itinerary first - it's a HUGE country (it's easy to underestimate the vast distances) so even if you're based out of Buenos Aires (BA), it's likely you'll have to pick another base if you want to see any other part of the country (every internal flight goes through BA as well which is inconvenient, but that's what it is). You'll be going in their summer, which means high temps and quite humid in BA at that time. http://travel.usnews.com/Buenos_Aires_Argentina/When_To_Visit/

I would highly recommend the Footprint Guide to get you started thinking on what you want to see. I went at the end of May (their Fall, very pleasant) and just covered the northwest (Salta/ Cafayete/ north Ruta 40 region) and Iguazu Falls for 2 weeks. I had to book 2 internal flights due to distances involved (the area around Buenos Aires is "pampas", flat ranching land so you need to get way out to see mountains). It was a complicated itinerary and way too much driving. The scenery was spectacular though - I probably wouldn't have done a less hectic trip. You could easily just spend a week in Buenos Aires but the beauty of Argentina lies outside the cities IMHO.

If you go, it's also worth reading up on their economy. It's in the tanks (has been for a long time since they defaulted on their loans in 2001) and they've had multiple exchange rates for their peso (black market rate and official rate). Who knows what it will look like in 2017. Overall, it was a place where you get a lot of value for your money and impossibly beautiful scenery.