When Martine and I went to Argentina in November 2011, we bypassed San Carlos de Bariloche because it was a disaster zone due to the eruption of Puyehue/Cordón Caulle in neighboring Chile. The Tren Patagonico between Viedma and Bariloche was shut down, and the whole State of Rio Negro was essentially shoveling volcanic ash. Instead, we went to El Calafate to see some spectacular glaciers such as Perito Moreno. It was worth it, but I want to see Bariloche, and not only Bariloche, but take the Lakes Crossing over into Chile and perhaps spend some time on the Chiloé Archipelago off Puerto Montt.
It would involve a crossing of the Andes by a combination of bus and boat (!), The Lake Districts of Argentina and Chile have some beautiful waterways, and the two-day Lakes Crossing looks interesting. I can always take a bus back without spending quite so many pesos.