Visiting Argentina in summer (i.e. January to March) means going to places that use to be crowdy, particularly in El Chalten and Calafate. I was there last year but in April, probably the best time to see fall colours and less people......trekkings in El Chaltén are well indicated and people there are very very nice. El Calafate has only the Laguna Nimez if you like to see birds.....the only reason to go to El Calafate is because it is the nearest place to the glacier Perito Moreno where you can find a place to stay....and you have to book your flight quite in advance....after seeing the glacier (which is marvellous) near Calafate, El Chaltén is THE PLACE for lanscapes in that region....very small town, so you have to book also in advance. I would recommend you to rent a car in Calafate, so you can go everywhere freely (there are buses but with restricted time tables and once you are in front of the Glacier you want to stay as much as possible there...). In El Chaltén mobiles do not work at all (nice thing, at least for me) and internet could be slow (but possible). Iguazu Falls are also amaizing but in summer is very hot and wet.....and although is not the usual place for argentinians in summer, it can also be crowdy (vacations there).
Other places that you can visit in Argentina are: a) Peninsula Valdez (also Patagonia) and see orcas and sea lions. In February you can go there and Punta Tombo (plenty of Magallan penguins....i.e. about half million!). In Valdez there is a private place (Estancia Rincon Chico) that offers you accomodations and meals, and it is the best place to see sea elephants. In general, I would say that Valdez is better from July to October, as you can see the whales (lots of!) and navigate among them. b) on the west you have a place called Malargüe that is a wonderfull place for landscapes, a region of volcanic origin, so it is like a black and yellow desert (this because of the small plants that grow there). c) in the east I would suggest Esteros del Iberá, that works fine for every season....plenty of nature and wildlife....no petrol and mobiles there, so you arrive by a transfer from the lodge you have booked (no hotels at all...only some lodges...so a very very quiet place, far from technology and civilisation....very nice people there...); c) in the north you have the Andeans landscape, the famous Quebrada de Humahuaca (a UNESCO world heritage site), Purmamarca and Valles Calchaquies, that offers you a landscape of a very dry site but plenty of colours.
So, you see.....going to Argentina means a lot of possibilities for photography....from wet to dry, from cold to hot, from greenish to yellowish places.....particularly from January to middle March is when the local people go to those places (particularly to the south Patagonia), so think about it. Argentina is not a place very well prepared for tourism, so in the high season it is complicated to find a hotel in the most visited places if it was not booked previously. I use to go to Patagonia in February, but always to less known places. One of the interesting things about Patagonia is that it is so vast that you can always visit something different where tourists usually don't go......but it also requires to take your time....(two weeks at least!).
Sorry if I was a little long, but I wanted to give you some details particularly about what you can expect from Argentina.....