Two full days is what Iguazu needs — one per country. The Argentinian side is a park of trails and catwalks that put you directly above the water, and it fills a day on its own. The Brazilian side is the panoramic one, and because everything there sits along a single road, the falls, the bird park, the helicopter flight and the boat ride all fit into one well-ordered day. This is the itinerary we run most often.
Order matters more than people expect: on day two everything sits along one road, so running it in this sequence is what makes four attractions fit comfortably in a day instead of three in a rush. Arrival and departure airport transfers are included — the trip starts when you land, not when the touring does.