Sadly in Buenos Aires I had to leave my cruise ship and find a bus to Puerto Iguazu to continue north. If I were to stay in Buenos Aires, there are over 1000 hotels bookable online. If you like steaks, then there is no better place than Argentina to enjoy one (maybe Uruguay). They call a steak; bife de chorizo or lomo de chorizo.
I took the overnight Rio Uruguay bus to Puerto Iguazu from Retiro, Buenos Aires. This was a 17 hour service which cost 868 pesos. The bus was luxury, meals included, lots of leg room and the seats went back far enough to have a good sleep, they call this a semi-cama service in South America. I recommend you use this type of bus as much as possible whilst traveling in any of the South American countries.