My wife and I spent two nights (pre-cruise) at the Sheraton on the Argentine side and thoroughly enjoyed ourselves. The first day we explored the Brazil side of the falls, took a jet boat ride up the river that went partially under the falls, and hiked. We spent the second day exploring the Argentine side which is a convenient walk from the Sheraton which is located in the National Park. Late that afternoon, we caught a flight back to BA.

Although we used a private guide, the Sheraton has an excellent tour desk which offers group tours. The Sheraton is a good hotel with great balcony views of the falls, a fine restaurant, beautiful grounds and a nice swimming pool. It is also located reasonably close to the airport on the Argentine side.

It would be a mistake not to visit both the Brazil and Argentine sides as the views are quite different. You will need a visa to enter Brazil.