I have traveled to Brazil 2 times now and visited Rio, Salvadoir, Busios, Ilha Grande, Sao Paulo and Paraty.
My favoutire was Ilha Grande, but to be honest all the coast is filled with paradise beaches.
It rains a lot in Brazil, so be ready for that. My wife wanted a beach vacation, but 5 out of 8 days it was raining! But brazil is not only about beaches. the country itself is huge both culturewise and undustrial wise. Its amazign.
if you want expert advice the following links are a good place to start. You can even have a travel advisor answer all your questions for free:) ..
Richard Leon
www.peruforless.com