Visiting Sao Paulo on March (São Paulo)

Hi!
I´m going to Sao Paulo in March for 7 days and I was wondering if you could give me some tips about where to go (and where not to go). I´m going for a training for 4 days so I´m looking for things to do at night (past 6 o clock) and for the whole weekend after the training. I like arts, nightlife, some trekking and I would like just to get to know the city and where to hang out.
Hope you can help me :)
Thanks!
Regards,
Cecilia