Update regarding the Amex Centurion Lounge in T1 -- the previous landside location has closed, and Amex is instead offering access to the new Bradesco lounge in T1 airside.
Links (in Portuguese):
http://www.bradesco.com.br/html/clas...n-express.shtm
http://www.melhoresdestinos.com.br/b...guarulhos.html