I would pay a day-use for the hotel inside GIG which is located in Terminal 1 (Luxor Hotel). The hotel is horrible, but at least you can get a bed, sleep and have a shower. Plus the restaurant of the hotel has a nice steak which you should try. I think the hotel day-use rate is about R$200.
http://www.luxorhoteis.com.br/br/hot...eiro/index.php
Rgs,