If you pop over to Argentina to see the argentinian side of the falls (and you should do that) then you should either change some money in to pesos or just use creditcard as the exchange rate they give you for reais there is very very bad.
Generally speaking 1 real is around 2,5 pesos but most shops and cafes on the argentinian side of the falls will give you just 2 pesos for one real so that is a 25% loss if you pay in reais.
So make sure to carry either some pesos or a credit card if you pop over to Argentina for a day.
Supposedly known - and popular among the local (brazilians) - for its bargains, Ciudad del Este is one of the attractions you can book for an afternoon of shopping. Firstly, the traffic jam into Paraguay is quite a hassle, and the city itself (not even 90 years old, so no historic or original buildings and such) is a busy, dirty, chaotic and crowded place. We did not feel unsafe or anything, and the people who bother you to buy their garbage were not even that aggressive, but I am pretty sure that any electrical appliance you would buy there will die on you before your flight back home. Besides, the amount of fishing rods, calculators (!) and other uninteresting items you could buy is staggering. I wound up buying a souvenir of Paraguay in Argentina, at the three borders monument (we saw the Brazilians side and the Argentinean side, and we strongly recommend the Argentinean side (more souvenir shops, more choice, nicer foto opportunity, more relaxed place). Ciudad del Este; not worth the trouble.
Unique Suggestions: If you really want to set foot in Paraguay, get a guide who can bring you to the a smaller Paraguayan waterfall in the jungle. At least the nature is pretty.
Fun Alternatives: The alternative.... if you come from a country like me, a cold and rainy country, a nice alternative can be just sitting by the pool, drinking cocktails and enjoying the sunshine. In this kind of beautiful weather... who wants to be out and about all the time anyways?
Some years back, it was decided by people who really should know better that Foz do Iguaçu needed to have a new attraction, especially a new attraction that would really draw people to the Point of the Three Frontiers where it is possible to see Argentina, Paraguay and of course Brasil where one is standing.
Obviously, being able to one-up the other two countries with a bigger, better monument of some sort was the primary goal, and any actual benefits achieved by such a tower were really beside the point.
Thus, the effort to build a structure that can at best be described as the Space Needle of South America (because that is what it appears to have been modeled after). The site chosen was, of course, right on the grounds of the Ponte do Tres Frontieras - that is the dedicated memorial park where one can see all three countries.
Unfortunately, after the supports for the tower got to be about 10 feet tall, the effort to build it stagnated and thus what the signs proudly declare to be THE TALLEST TOWER IN LATIN AMERICA!!!!!! is an unfortunate pile of uncompleted dreams and debris, with even a few sections of the sign having been stolen in recent years.
However, at least you can enjoy the nice, simple monument to the Three Frontiers as it always has existed, pretty much. The failed tower attempt is thankfully slightly up hill and only consumes a portion of the parking lot.
It was not a real trap, only we found it did not have good deals for people from North America. The free shuttle picked us up from the hotel. It is something to do in the evening. There was a nice coffee shop, we had coffee and watched big screen showing Bee-Gee and Celine Dion.
In our case, the tour of the Itaipu Dam was thrown in as a 'filler' (along with downtown Foz do Iguacu) to make up a full-day when touring the Brazilian-side of Iguacu Falls. This is the case with just about all tours, because our small mini-bus was dwarfed by the 14 other full-size busses that made all the same moves we did while at the Dam.
After being shown into the Visitor Centre, you are subjected to a half-hour or so film (we came in part way through) extolling the wondeous virtues of the Dam project. There was not a single negative word about the issues that must have been involved in flooding such a large area of forest. The film really was like something straight out the 1950s where all is happiness and light!
Unique Suggestions: From there, you hop back in the busses and head off in convoy to tour the site. First stop for us was the view of the Spillway, where a short period is allowed to get out and take some photos. Back in the bus again for another stop at a covered seating area to allow some long distance views of the powerhouse part of the dam.
Finally, a drive down around the power house and past the huge penstocks (or tubes) feeding down to each generator. A final pass along the top of the dam until reaching the Paraguay border in it's middle. Then, the convoy heads off to Foz for some City explorations.
It was a cursory trip, but I've seen enough dams in my career, so I was happy to be on the road. Overall, it was worth it, especially since it was free!
As a former Law Enforcement Agent, I am sad to admit this: many travel agencies do not warn you about the night life in Iguassu Falls (Foz do Iguacu). I've seen and helped many tourists that falled into some traps. Ill talk about this later, but for now: always avoid both rivers nearbies (is this the right spell?), even during day. There are two rivers in Foz do Iguacu: Rio Paran?and Rio Iguaçu. Avoid these places and nearbies, because there are some "favelas" (dangerous places where SOME criminals live - nice people live there too). If you get too close, you WILL be robbed, I guarantee. Other places are safe, but due to low resources, these places can't be 100% protected by police officers.
Unique Suggestions: If you are close enought to see Iguaçu River (Rio Iguaçu) and the city across it (Ciudad del Este - Paraguay), then you are a target for drug addicted children that will rob you. The best thing to do in this moment is turn around and go downtown. Do not hesitate, and do not stop or talk to any poor child, because there can be some adults covering them in a robbery. If you get too close to the river, you will be only 2 - 3 blocks from downtown, where you will be safe.
Fun Alternatives: If you want to see both rivers without danger, you there are safe places. Send me an e-mail and I will teach you how you can see both rivers that separates the 3 countries borders (Brazil, Paraguay and Argentina) in a safe and guaranteed way. There is also a tourist spot called Marco das Três Fronteiras, where you can see all 3 countries at the same time, and the place where both rivers meet each other. That is a safe place, for there is a place where the local budget can afford placing some City Guards (their objective is to protect the buildings, but they will protect all tourists).