I wanted to pass along a very good site and business for finding apartments in Buenos Aires. This past December I was looking for a two week stay near the city center and found Let's Go Argentina website: http://www.LetsGoArgentina.com/
They offer apartments all over the city and I was very glad to find one near Recoleta in Barrio Norte. I was put in contact with Santiago who runs the company with a team of employees. He was very professional, and sweet, as he met us at the apartment after giving us very good directions to get there, as we were first time BA'ers.
The apartment was very spacious, clean (and a cleaning lady came and helped during our stay which was over the top!) and perfectly situated in the city. Literally, we walked everywhere and were able to enjoy the A/C upon our return. We were provided a list of the sites, restaurants and bars that only a local would know about. I am still telling friends about the parillas that Santiago recommended. We would never have found those anywhere else.
The apartment was very spacious, nicely decorated and definitely a great place to feel 'local' while taking in the city.
The team at LetsGoArgentina was professional and very responsive to any questions. The added individual attention will definitely get me to use them again when I return.