Whatever you do in Puerto Iguazu, DO NOT BOOK with Venteveo Turismo, the travel agency at the main bus station who scammed us and other travelers we talked to. We booked transportation through them. They are 3 of them: there is the old guy, the teenage crisis girl and the smiling lady, we booked with the last one.
We have been travelling over South America for a month and we had excellent experiences with buses. We always booked our own tickets but we were limited in choices for our Puerto Iguazu to Bonito itinerary because Carnaval time is an incredibly busy time to book anything in Brasil and we were in Argentina trying to book Brasilian buses.
The deal from Venteveo Turismo seemed perfectly fine: they pick us up at the hotel in a van to get to Foz Iguazu bus station on the Brasil side and they book our bus tickets ahead of time to ensure seats. We payed them 300 pesos per ticket (+10% surcharge for using credit card) which incl. the drive to the Brasil bus station. Another Canadian we met paid the same amount with the same agency without the driver.
The day of the trip, a driver came to pick us up in a jeep, got us through the border, got us the tickets in the bus station. Once we got in the bus, that's when the nightmare begins; we realized they got us the cheapest, worst ride possible to make a better premium. The Medianeira bus smelled like the washroom was not clean in years (they put us in the last seats next to it), there was no A/C, and it would only go 50-60 KM an hour. They switched busses after 3 hours but still no A/C in the other bus. Some people were standing because there were not enough seats in the 2nd bus layout and it created friction. The bus stopped at a minimum 20 times during the 17 hours bus ride, sometimes to pick up passengers but most of the time for no apparent reason other than the driver getting a smoke. We were told we would get to Campo Grande at 6am, we got here at 9:30am. It was one of the worst bus experience. My advice, go to the bus station and get your own tickets and check how many times they stop.