I never really understood tourism, as a concept. My aim has always been, when visiting a country for a limited time, to see some landmarks PLUS to meet the locals who have been through the worst or the craziest and have stories to tell. I'm not gonna bore you with stories of my life. Enough to say, La Boca is absolutely unmissable, if you want to know something about Argentina, despite its ever increasingly commercial onda. There's still ghosts talking. Plus I also like crazy places like Campora meetings, illegal chapels of Gauchito Gil, the smoking tombstone of Carlos Gardel in Chacarita, Villa Freud etc. I'm a freak, I know. But that's how I get to know Argentina, I'm not expecting anyone to do the same. I want to understand (not necessarily agree with) the soul of the country.
Another super-interesting spot I would recommend is the Campamento Toas in Plaza de Mayo, in front of Casa Rosada. If you like it or not, there is a reason why these veterans are allowed to camp in front of the presidential palace. I'm not necessarily saying I share their view of the world. Yet, these guys were the soldiers in the Malvinas conflict, and they are happy to share their stories, first hand. If you're lucky, some of them even speak English.