I have a similar issue to Gablson...yet not quite.
I'm traveling from Rio to Sao Paulo to catch a flight early morning around 7. I'm not sure what the bus schedule will be like from Rio to Sao Paulo, but I'm assuming I will have to stay the night before I catch the flight near Guarulhos Airport. I'd like to spend as little money as possible and also guarantee I won't miss my flight (so the shuttle thing from the hotel will probably be best...?) Any suggestions?