Congonhas Airport
Though Guarulhos International Airport services some domestic flights to other Brazilian destinations, the Congonhas Airport (aeroportocongonhas.net/en) deals with almost all domestic flights to and from Sao Paulo. Congonhas is only eight miles outside of the city, easily accessible by taxi, bus, or the metro. The airport doesn't have the same range of service as the international airport, but its proximity to downtown Sao Paulo makes up for its limited services. You'll still find a few restaurants and a couple of travel agencies for booking onward domestic travel at Congonhas.