To me, there is a difference between graffiti and street art. Street art goes above and beyond graffiti, and is a pleasure to look at. There is a LOT of street art in Buenos Aires, and some truly amazing street art in San Telmo. It is easy to just walk up and down the streets of San Telmo, and check out the buildings, and news stands.
If you are up for it, there are guided tours as well. Here are two that I know of:
If you are going to walk by yourself, I would recommend the area surrounded by Belgrano and San Juan, and Chacabuco and Defensa. That’s a 8 block by 4 block area, so it is a LOT of walking if you try to walk all of them, but, if you break it down into a couple days, it’s not too bad.
Have fun, and if you get hungry, there is a place between Chile and Independencia, on Peru, that has cheap, good sandwiches and Choripan. The owner is a super nice guy as well.