El Viejo Almacén is one of the most historic tango shows in Buenos Aires. I love their show in one of the oldest buildings in San Telmo.
The dinner service is before the show, across the street. You can easily opt for just the show and dine elsewhere (La Brigada and Desnivel just a few blocks away make a mean steak).
For ease, include the dinner to have your entire night planned in one fell swoop.
The venue for the show is intimate, with individual round tables. Wherever you are seated, you'll be close to the stage.