Have visited Brazil several times, here are some of my thoughts.
On our last trip to Rio we stayed at the JW Copacabana. The hotel is good, but very expensive if you are not using points.
The location is good, this is where you want to stay particularly if this is your first trip to the city.
The concierge lounge is very good, (I think it is on the 9th floor & we stayed on the 7th) great view over the beach. The staff were friendly and there was plenty on offer in terms of food and drink.
The rooms are fine, not overly big but do not have outside balconies.
If you are unable to use points and the price is high a good alternative is Porto Bay Hotel. The rooms here have outside balconies and the breakfast is very good.
We have walked up and down Ave Atlantica several times and viewed the hotels and many are pretty ordinary to say the least for the prices they charge.
In general Rio is an expensive city.
We walked throughout the city centre area, Copacabana & Ipanema and hired a driver to take us to some of the further away places.
We rode the subway which seemed okay. You can get from the Copacabana area to the central area http://en.wikipedia.org/wiki/Rio_de_Janeiro_Metro
Closest station to JW hotel Siqueira Campos
In Rio there are the sights like: Corcovado (Christ the Redeemer) http://www.corcovado.com.br/index_ing.html, Sugar Loaf http://www.bondinho.com.br/en/. With both of these places it is important to visit on a clear day otherwise you will be wasting your money.
A nice place to visit is Santa Teresa http://en.wikipedia.org/wiki/Santa_Teresa_Tram. it looks like the tram is shut down though.
This house is worth visiting: Museu Chacara http://www.museuscastromaya.com.br/chacara.htm
The cathedral http://en.wikipedia.org/wiki/Rio_de_Janeiro_Cathedral is located near the Tram stop.
Copacabana Fort http://www.fortedecopacabana.com/
National History Museum http://www.museuhistoriconacional.com.br/ingles/index2.htm
Fine Arts Museum http://www.mnba.gov.br/
You can take the boat to Niteroi and see the Oscar Niemeyer designed Contemporary Art Museum http://www.macniteroi.com.br/.
The structure is better than the collection. You can also get some nice photos from the building.
A few restaurants: Porcao Flamengo http://www.porcao.com.br/, great food and view from the restaurant. Better to go at lunch time as you will be full leaving here.
Casa de Feijoada in the Ipanema area http://www.tripadvisor.co.uk/Restaurant_Review-g303506-d1062251-Reviews-Casa_da_Feijoada-Rio_de_Janeiro_State_of_Rio_de_Janeiro.html
In Santa Teresa: Aprazivel http://www.aprazivel.com.br/aprazivel.htm nice food and good views.
A good day trip from Rio is Petropolis: http://en.wikipedia.org/wiki/Petr%C3%B3polis if you wish to know anymore I can elaborate on the sights we saw.
When we visited Bonito http://en.wikipedia.org/wiki/Bonito,_Mato_Grosso_do_Sul we did get yellow fever shots.
I have not visited Iguazu Falls myself, but my wife has so I can find out further information if you require.
Iguazu falls are wonderful. Try to visit the Argentina side of the falls. Remember that you will be in a city (Foz de Iguazu) where basically has frontier with Argentina, Paraguay.
It is a safe place. Paraguay is a little mess (for shopping electronics is the best place).
Also, visit the Itaipu plant. Amazing!
Rio de Janeiro: go with a guide always. It is nice, but it can be dangerous for foreigners depending the area they go. A guide is a must.