Not knowing where you are from or what kind of business you are in, it's hard to make a recommendation about clothing. I find in my area of business, contemporary art, people dress a little more casually in summer in Sao Paulo than they would in Sydney which is where I'm from. Looking at the crowds in the financial area, however, there's no difference to what I would expect to see in an Australian city or a European one.

The Jardins area is a good place to stay, or Villa Magdalena, and I found the Unibanco guidebook (available from Amazon) the best guidebook. Timeout guide also looks good.

It's helpful to have a bigger map than any guidebook has, to put the districts together. There's a free Art Map available from all art galleries that is extremely useful.

Business attire is similar to the US. Lots of people in suits. Just remember - seasons are the opposite of the US (in case you're from the US).

Sao Paulo is the 3rd largest city in this world of ours. It's also the "business center" of Brasil; thus the attire would be similarly to what one would wear in New York City, Paris, any major city of this world.

I thank Debi for citing that the seasons are indeed reversed if you're coming for the Northern Hemisphere!

<When I was going to live in Australia for two years, teaching in a public high school, I had to go to San Francisco for an interview with a member of the Australian Consulate; I dressed by wearing a suit, tie, goodlooking shoes, etc.>

If you are a woman, you'd wear the usual "business attire" as you would do in your native country!