While everyone agrees that the Argentine falls—about 80% of the total—are the finest, folks who want to enjoy those panoramic views over the cascades, in particular the epic vista above the Garganta del Diablo, will want to head to Brazilian. In general, it's very easy to travel between the two countries, with border formalities streamlined and simplified as you take the twenty-minute bus ride (US$5) across the Iguazu River on Tancredo Neves International Bridge. You can be asked for a yellow fever vaccination card, but this is rarely an issue for obvious day-trippers.

The main problem is Brazil's reciprocal visa policy, enacted in June 2010, which requires foreign nationals to undergo the same visa restrictions that Brazilians endure when trying to enter your country. Depending on your nationality, it's either an easy jaunt or expensive bureaucratic hassle to visit Brazil. US and Canadian citizens, for example, must arrange their visas in advance, and pay US$130 and US$65, respectively. That's pretty stiff for a day trip. Citizens of the EU, UK, and most Latin American countries, on the other hand, can cross the border without a visa or fee.

Taxi drivers may offer to take you across the border without a visa, and this has been done successfully. That said, there may be better ways to spend your vacation than in a Brazilian jail. Please pay the fee, or stay on the Argentine side of the falls.

While Paraguay doesn't have a view over Iguazu Falls, Ciudad del Este is a quick trip from Foz de Iguacu, Brazil, either by bus or ferry. The second-largest city in Paraguay is probably best known as a tax-free shopping destination, popular among Argentine and Brazilian tourists looking for great deals on electronics and other big-ticket items. There's certainly some waterfall tourism here, but since you have to enter Brazil to visit the national park, most people stay here or in Argentina.

In addition to the gritty city and its endless assortment of shopping centers, this is also a great base for exploring Guarani culture. About 95% of Paraguayan speak Guarani, and you can visit the Museo de Tierra Guarani (Museum of Guarani Land) in town, or book a tour to Refugio Tati Yupi, an autonomous wilderness reserve with hiking, camping, horseback riding, and other facilities for guests.