Getting to BA is very easy from Santiago, and it's possible to go by bus (24 hours) or fly (2 hours). Given that I was taking time off work, I decided to fly, and LAN (the Chilean national airline) broke all stereotypes with an amazing flight that was cheaper and better than any European flag carrier. Also, the views as we flew over the Andes were pretty stunning.
The next day we met with Lucas, Greg's contact at the University, who took us out for lunch at a very edgy vegetarian restaurant in Palermo SoHo, after which we headed into town again. We went to el Ateneo, one of the best bookshops in the world, and housed in an old theatre, then got the metro into the Microcentro. We saw Casa Rosada, the seat of the Argentine executive branch, several churches, Puerto Madero, the "hip" docklands area, and then headed down into San Telmo, a very bohemian barrio of Buenos Aires.