I agree with most folks here. I've been to brazil once: Rio and Sao Paulo. In general, Brazil didn't make it to my fav destinations. That said, Rio actually wasn't, especially after visiting Sao Paulo.
As OP said, he was planning to spend 2 days in Sao Paulo. I honestly a day is enough and would spend longer in Rio.
I recently went to Sao Paulo and spent 2 days, I think that's more than enough. The complain I have is the air quality. Also, there are homeless everywhere. Not to mention
someone tried to snatch my phone when taking a picture. I'm not suggesting Brazil is unsafe. I actually feel ok - no one tried to scam TBH. But still - be safe and cautious.
Apart from there, some landmarks are beautiful. Here are some pics:
The Theater
The City
The Cathedral