La Casita De San Telmo is a family home with several rooms available to let. Some rooms have their own bathroom and there are also shared facilities. There is a good sized kitchen which is available to all, and on occasion the family will invite you to dine with them. Also, there is an in house computer with good speed internet access, and I believe they also have wireless access. There is a nice indoor garden (with an available barbecue) and soon they will have an available dance studio should you wish to practice or schedule lessons with tango or something else. They have a website easy enough to find online though I'm guessing I can't post the URL here.
Personal info: I spent a month here on a trip where my focus was specifically to study tango and was very satisfied with my decision. The family who owns the house has a rich history with tango (the matron and her son are both singers) and the location is close to many tango venues, and also many other non-tango areas of interest (antiques market, Puerto Madera, etc.). I was treated very warmly and assisted in whatever I needed, yet also was given all the privacy I wanted. My primary host was a guy named Pablo (the son) who spoke very good English. My room was spacious and warm despite the winter temperatures, and the hot water in the bathroom worked fine (I've found this isn't always the case when I travel). The bed in my room was big, clean, and comfortable, although there are other, smaller rooms with smaller beds, I assume at a lower rate (however, this being Argentina, prices for accommodations are a bargain for many travelers from abroad--right now the general room rate at La Casita is about 20-25 US dollars per day, although it should be noted that the cost for accommodations in Buenos Aires is constantly in flux). Anyway, I had such a positive experience here I really wanted to share it and get the word out about this place.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.