The best website to buy flights to Brazil is not Kayak, Expedia, or even the airlines themselves.
The best place to buy flights to Brazil is BACC travel. They have the best deals. You can also work with them to combine specific flights that are not coming together in the website search.
They also have decent costumer service in Portuguese and in English. As with most costumer service, it greatly depends on who you get on the other end of the line. I had much better experiences in previous years, but this time it was not bad.
They canceled my troubled flight free of charge because of that crazy connection in different airports.
Now if you are flying inside Brazil, try going straight to the airlines - voegol.com.br, voeazul.com.br and tam.com.br - or even kayak.
The reason for that is that bacc doesn't show all the airlines that do flights in Brazil.