How long are you planning to travel?
To drive in Argentina you'll need an international driver's license (and remember we drive on the right...mostly).
If you have one, you'll see more and will be more flexible. But I wouldn't do it alone, as you may feel lonely. I mean, travelling by bus you'll meet more people.
Mendoza to Salta is where most of the wine comes from! If you're into wine, it can be fabulous.
From Mendoza to San Juan I would go via Uspallata, Barreal and the Calingasta valley. It's gravel road for the most part of it, but the landscapes are just gorgeous. And it is lonely...you won't see more than 1-2 cars. And you can't drive very fast, as the gravel can be treacherous. I did it with a small Corsa and it was ok. Barreal is a nice sleepy town, where you can try some of the local especialities. But forget this route if travelling by bus. In that case take one of the frequent Mendoza-San Juan buses.
Around San Juan there are a few fine wineries, like
Augusto Pulenta or
Graffigna. There are some tours from San Juan, but I don't know enough to recommend one. It is also possible to visit from there the Calingasta Valley, in case you haven't travelled through. From San Juan you can also take a tour to visit Ischigualasto (Valle de la Luna). I met some Germans there who have talked to a taxi driver in San Juan city and he organised the trip for them. At the park entrance he gave them his car and he stayed there sleeping under a tree until the Germans came back

The base for visiting Ischigualasto is San Agustín de Valle Fértil (there is acommodation there too). I don't know if there are buses from there to La Rioja, but it would be great. If you're driving it is easy then. Check on the internet, but Talampaya could also be interesting.
I recommend visiting Chilecito, in La Rioja province. Other than for the wine (they have some very good torrontés riojano) it is a peacefull little city, with superb views to the mountains and a
very laid back atmosphere. I love it. Nearby Nonogasta is beatifull too. So different from BA!
If you're driving you can take the road to Tinogasta, in Catamarca province. Otherwise head from Chilecito to La Rioja, and further Tucumán, staying in Catamarca if you like.
I don't like Tucumán city very much (it's like a small BsAs), but there is a wonderful road going from the city to Amaichá del Valle (via the Quilmes ruins) which is one of my favourites. Amazing and changing landscapes. I don't know much about buses going there. You may contact
this site (or at least have a look at the pictures!).
Cafayate would be a very nice form to enter into Salta province. Lots of wines to be tasted, including the best torrontés. Salta is a beautiful city, and from there there are lots of minibuses doing the usual tours: Cachi (do it as first) and then San Antonio de los Cobres via Salinas Grandes and Purmamarca (many people get sick on this trip, as it crosses areas which are well above the 3500 m asl - 4200 m I think). From Salta you can also visit on a third day the Quebrada de Humahuaca, which is a must if you are there. The way back across the yungas (jungle) is amazing as you travel across very dry landscapes first to be in a matter of minutes in the middle of a tropical forest!
You may travel from Salta city to San Salvador de Jujuy first, and use it as a base to explore the province. Salta is definitely livelier than Jujuy, but it depends on what you're after.
I wish you a nice trip, it is a beautiful region. (have I mentioned there is lots of wine to be tasted there??

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