I consider the falls to be the most beautiful natural wonder I have ever seen.
I stayed a couple of years back in
http://www.tropicalhotel.com.br/. This is a beautiful pink stucco hotel built in 1958 and within the park. Walkways allow you to wander down to excellent views of the falls; the sound lulls you to sleep at night. The hotel has a truly South American flavor and excellent service. The breakfast buffet is tremendous, drinks by the pool, toucans in the trees - I WANT TO GO BACK. The concierge desk can handle all of your questions.
Someone asked about the Brazillian visa, so they must not be approaching from the Brazillian side. I bet they can work out some special thing as noted by another poster. If I recall, there is a museum and visitors center on the Argentinian side of the falls, but I recall my walk of the falls beginning on the Brazillian side.
Just fyi, I flew in from Sao Paulo, and flew back into Rio with a stop in some city along the way - did not deplane. I must say, all the duct tape I have used in my life would not surpass the amount I saw holding the interior of this old 707 together, but we made it!