Eight days in Argentina/Nearby

Wife and I are working on an 8 day trip to South America. We both love just "going with the flow," good food and wine, and new experiences. We don't need to check a lot of boxes or hit all the "must see/do spots." If this helps, we have a second home in New Orleans and enjoy going there and just doing whatever pops up, as opposed to creating an itinerary when we visit. That said, we know we need to create one (or a semblance of one) for this trip.

We are definitely flying into Buenos Aires and spending a good bit of time there. I would much rather have a relaxing trip that doesn't involve a lot of moves, so if we visit another spot, it would only be one other city. So my question is this. If you had 8 days, would you just stay in Buenos Aires, possibly taking a few day excursions from there? Or would you add a second city? The idea of not having an additional flight in the middle of the trip is really appealing. Initially we thought about Montevideo, Uruguay, and getting there by ferry, but I'm not sure now.