The fact that you're asking the question would lead me to recommend that you hire a car and driver. I agree with the comments about rough roads and also about some challenging, narrow mountain roads. We were there five years ago - great visit. We spent a day or two in Salta at the beginning, then hired a car and driver to stop in Purmamarca, take us up to see the salt flats and drop us at our hotel. The same driver picked us up a couple days later and drove us back to Salta, where we spent another few days before flying back to BA. Many of the "paved" roads in the mountains were only really about one and half lanes wide, and the yellow line down the middle was just a suggestion, even on blind curves.

I'd have to dig around to find the name of the English-speaking driver we used, who was recommended by an acquaintance who had just visited there a month or two before we were. I suggest just checking Trip*visor for more recent suggestions.

Great local food in that region, BTW, not all the European-inspired dishes and heavy steak they want tourists to eat in BA.