Holidays in SP area (São Paulo)

Hi, I am planning a trip to Brazil in February next year. I will go to Manaus, after that to Sao Paulo and after that I would like to spend a week by the coast. I have heard Guaruja is good and have looked up different hotels there. Can you recommend any specific beach? What about Praia da Guaiúba (where I have found a very nice pousada)? Thanks in advance for your advice!
Pernilla