City Bus Tour (São Paulo)

I have a 4.5 hour lay over in Sao Paulo before heading to Florianopolis. I'm trying to find one of those quick city bus tours that give a quick overlay of the city, or one region of the city. My internet searches pull up larger tour packages for days or weeks.
Anyone know of any one of these tours? (sometimes they are the cheesy open top double decker buses.) Bonus if it leaves from the airport.

Thanks,
Nicola