Itinerary advice - Iguazu - BsAs

Hello all,

I've been searching the forums for advice on an itinerary from Rio de Janeiro - Buenos Aires and have formulated a vague plan.

My question relates to North East Argentina more specifically. I have seen various comments that state that there is not much to see between Iguazu and BsAs, however it seems to me that it is an interesting area. Most posters suggest a direct bus or flight from Iguazu to BsAS, so information is a little sparse.

I arrive in Rio de Janeiro on 12th Jan 2013 and must be in BsAs on 7th Feb 2013 to meet my Dad.

What do you think of the itinerary below?

Rio (6 nights)
Ilha Grande (3 nights)
Paraty (2 nights)
Iguazu (2 nights)
Posadas + surrounds (3 nights)
Resistencia/Corrientes/Paso de la Patria (4 nights)
Esteros del Ibera (2 nights)
BsAs (x nights)

This would leave me with 4 nights "spare". Is there anywhere that I should consider adding or shall I keep this time in case I feel like staying somewhere for longer than planned?

Thank you in advance for your help.