hi just came form trip to brazil, in Rio you can book for touristic tour , I went ot mountain of corcodova (christ statu) so beuatifull and also more beautifull sugar laof and you go by telefrique from mountain to mountain...I will not froget this trip all my life about sao paulo I visited for few days but it was family visit I didnt go out alot but I think not too much inetresting things I missed have nice trip and be sure you will repeat it! I just came and I am thinking to go back
Sao Paulo is the second largest city in the world after Mexico City. It's like Detroit, the industry and commerce city. Not much to see in tourism. Not sure if you meant 3 days in each city, but in Rio I would recommend staying at the Premier Copacabana Hotel, good location and accommodations and includes breakfast. Taking an organized tour by a local tour operator is the best idea. Rio does have its share of petty crime and it's best to be in a group. Enjoy!
Visit Rio, it is far more better then Sao Paulo in terms of tourism. Some of its beautiful attractions are Sugar Loaf Mountain, Cristo Redentor (Statue of Christ the Redeemer), Prainha Beach, Pedra da Gavea. Enjoy!!!