The Sheraton has special weekend rates in Brazilian currency if you call them directly on +55-21-2274-1122. At the moment the rate is R$390 (US$135) per night for Friday through Sunday, including breakfast and 'feijoada' (Brazilian dish based on black beans and dried meats; they do have other things as well) on Saturday afternoon lunch. The rate in USD is slightly higher: $169, but you can ask for the rate in reais.