I found your article through ballroomdancers.com.
This is the info I composed for a friend of mine. I thought it might help.
Are you happened to be a friend of Cheryl T? She mensioned about some one who was going to Buenos Aires. Good luck.

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Here are some info about Tango in Buenos Aires. You can buy B.A.Tango at the stands or obtain Tangauta at the studios for the locations. Cafe Tortini (everyone knows where it is) always carry Tangauta but others don't.

Place for Milonga
Mon: Re Fa Si I am not sure they are still doing this or not.
Wed: Estrilla/Viruta Younger crowd, informal
Thu: Niño Bien Very formal atmosphere; a class before the milonga
Fri: Estrilla/Viruta Lots of regular crowd
Sat: Estrilla/Viruta Lots of regular crowd

Practica
Mon: Gustavo/Olga Near San Telmo; lots of advanced dancers; I have never seen G&O there, however.
the address was 444 something. See B.A.Tango.

Cheap Hotel
Victoria Hotel Chacabuco 726 (@ Chile) tel. 4361-2135 US$15/person but discount for longer term
Cheap and better quality than any hotels I took a look for this price range. Majority of hostellers are either tango students or 'Japanese tourist'. It is in San Telmo (which is not the safest area) but walking distance to Niño Bien, Re Fa Si and Subte station (don't recall the name but 1 or 2 before Constitucion), but better to take taxi at night ($2). There are several Pizza shops around where you can eat 1/4 of delicious pizza for 50 cents. Other restaurants are extremely expensive in B.A. I was eating pizzas every day...

Tango instructor
I found Angel Coria was the best among I had. He was the '1ro bailador' in Juan Carlos Copes's class. He was acting in the movie, Tango here and there. He danced with the leading actress in the audition scene; it proves the quality of his tango. The best I like about is he put looots of emphasis on 'technique.' And his technique is very logic oriented. He offers group classes, but it may be a bit too easy for followers at your level. Since he does not work as 100 % professional, he gave me and my girlfriend a promotional private lesson for $40/h (cheaper than others asking $100). Both of us were very happy and ended up with 2 hours in a row. Ask him, telling I told you so.
Angel y Angela Coria
Phone: 54-11-4244-4626, Cell: 15-4098-4910
Jose M. Penna 748-(1832) Loma de Zamora
email: ayatango@uole.com