Book Shopping in Buenos Aires
To check out some of these small bookstores, head to SAN NICOLAS (the central area which is located west of Ave 9 de Julio), and focus your attention patricularly on Corrientes between Ave Libertad and Ave Callao and also on the area directly north (Lavalle, Tucuman). That's where you will find lots of specialized little nooks (specializing in everything from education to medicine) and a few larger ones, similar to Shakespeare & Co in New York. The most famous of the pack is Gandhi (Avenida Corrientes 1743), although it's probably pushing the definition of a nook.
Those missing their "Barnes & Nobles" will appreciate the local mega-chain called El Ateneo. Perhaps the most imposing Ateneo store (Avenida Santa Fe 1860, between Callao and Riobamba) is housed in a former theater. A beautiful sight. Here's what it looks like:
Another Ateneo location (and the one most frequently mentioned by guidebooks) is Florida 340, but I was too lazy to go in since I kind of dislike Florida street in general. There are other branches as well.
Finally, a big name in the city is Librería Rodriguez (Sarmiento 835) which also sells books in English.