Sao Paulo or Rio de Janerio?

I'm trying to convince my mom to let us go to Brazil this summer. I'm not sure if we should go to Rio or Sao Paulo. My brother lives in Sao Paulo, so we could see him. ( haven't seem him in a while) Or should we go to Rio, where all the fun is. We don't have enough money in the budget to go to both. I asked my mom which is more fun, but she says she hasn't been to Sao Paulo. I was thinking if we went to Rio, my brother could fly there to meet us. What should we do?