If wine is part of the tour, and you're passing through Mendoza, I'd have reckoned the must-see spots are O Fournier (ideally for a very long lunch) and Acheval Ferrer (ideally after you've seen some of the others, to help appreciate how differently they do things). There's a wine bar in town that does both tastings and helps with arrangements for visiting the establishments. If off the beaten path, we actually had rather a good time in Cafajate, which is a one-horse town in the best sense of the word, and very good for Torrontes.