After Peru, we flew to Iguacu in Brazil. The falls straddle the border between Brazil and Argentina, and Paraguay is just a few hundred yards up river.
Both countries have national parks surrounding the water falls. The Argentinian side has about 75% of the falls, and the Brazilian side has a larger park area with fewer falls. However, you can see the entirety of the Argentinian side from Brazil.
We arrived late at night so had dinner and went to bed. The next day was a full day tour of the Argentinian side. Then, the following day was a half day tour in Brazil, and then we were off to the airport for our flight to Rio!