My husband and I traveled to the Falls this past Feb and planned everything ourselves, it was pretty straight forward. I would recommend at least 3 full days to fully enjoy this beautiful area. We stayed for 5. I would also suggest staying on the Argentina side for ease in getting there, better exchange rates and better view of the Falls
A few important tips:
Remember there are 2 different airports in Buenos Aires. You will need to book from AEP which has the most direct flights to IGR. From there, taxis are plentiful, inexpensive and hotels are close by.
Wherever you decide to stay, be sure to book your reservation in Argentine Pesos at the blue rate not American Dollars! This is very important and will save you a lot of money. Not all hotel web sites offer this option. We stayed at the Loi Suites Iguazu Hotel which was wonderful and by using the Argentine Peso rate saved us nearly 1/2!
Once at the hotel, they immediately connected us with a driver who drove us to the Falls entrance each day (10 min drive) and picked us up. We arranged to use him exclusively during our visit and he was was happy to do so. Some evenings he drove us into town for dinner even on the Brazilin side. We paid him at the end of our visit which was very reasonable (trying to remember...all 5 days weren't more than the equivalent of $200US).
The Falls are magical and the people are lovely. Also forgot to mention, the food is fabulous!
Enjoy your planning!
Mary