By the way don't let me dissuade you from any punting but depending on how often you get the opportunity to go to BsAs it's maybe only fair to mention that 3 days is long enough to do Iguassú Falls (short domestic flight). You can see the glorious Argentina side, the breathtaking Brazilian side, do a waterfall at high speed in a motor boat or swim half naked in a grotto if you're fit.
A lot of the better BsAs brothels are daytime only though, so could cramp your style a bit if you have to rely on work days to go punting. San Telmo is cute to visit, market, tango in the street, or hot tango at night (taxis safest at night) but I wouldn't necessarily stay there.
When I stayed in Recoleta I ended up not leaving the area, which is ok (lovely area) but like several of the other suburbs feels very self contained. It's good to taste a variety. The brothel I tried there was good but very expensive. I'd say maybe work out the punting locales you want -- there's enormous variety -- and try to include some amazing non-punting stuff as well. (If you can dance a little there's also tango bars that go on all night, as well as high class traditional, but avoid the tourist show's apart from the San Telmo Square).
