Everywhere in BA is Tango. You can pay for a tourist show, see a cultural exhibiton at the teatro colon or see street performers.
Cafe Tortoni is a coffee shop that has a stage for Tango shows at night.
Also has t shirts,cups for gifts to bring back home to those who couldnt make it.
There are tourist places like Senor Tango and Piazzolla but then there are some milangros around town that you should also go checkout as well. Some will show tango mixed with salsa.
if you go to buenos aires, must go to Corrientes street, bohemian zone, and watch a tango dancing show...that's life!!!