We had a fantastic time in Ralf's beautiful apartment in Palermo Soho! The night we arrived there was a crazy thunderstorm and we were able to experience it from the 19th floor with 270 degrees of vision.
The location is quite perfect. Close enough to Recoleta/Retiro/Microcentro, but also tucked away from the street and near the Subte and great restaurants. We betrayed our American-ness by getting Starbucks at the Arcos District (5 minute walk), and using Uber to get to the Airport (highly recommend). It really is a superior way to visit Buenos Aires. We wouldn't hesitate to come back.