Howard Barsky, my friend from L.A., has danced tango longer than I, and has danced in the milongas around the world. He comes to Buenos Aires twice a year, and has put together a useful interactive map of all the milongas and tango shoe stores in town. Not only does it help you when you're deciding where to stay, once you're here, it's useful for where to go and how to get there for your tango needs.
He's also a respected artist, as you can see below:
This post will eventually be in the archives, but there is a permanent link on the sidebar for MAP.
Thanks, Howard. This will be useful for many people.