T-Mobil International Pass
I have the T-Mobil Magenta Unlimited 55 plan which costs $50/ month for 1 phone or $30/ month per phone for 2 or more phones. The plan works automatically upon arrival in Brazil, however, download internet speeds are incredibly slow. Of course, WiFi in most 4* & 5* hotels is fast and reliable, but in a bar or restaurant speeds are low and asking for WiFi pw's gets to be a pain in the ass. T-Mobil has a solution for this problem. They call it their International Pass. It costs an additional $50/ month, but you will never complain about slow download speeds in Brazil again.