Did that same bus ride but in reverse. Although I broke it up to 3 sets. BA-Corrientes, Corrientes-San Ignacio, San-Ignacio-Puerto Iguazzu.
I also had a terrific time in Buenos Aires. Stayed in a hotel on Avenida de Mayo called Hotel Hispanico...very nice and comfortable. If you can and you enjoy tango, there's an awesome Milonga in Palermo that happens pretty much every evening. Not too many tourist and many locals. A really really good time.
Still envious but I'm glad you're having an awesome time.