I lived in PoA for 6 months. Night game would be the same all over the country, but day game would probably work better in Goiânia, because people are less reluctant to talk to strangers. On the other hand, I guess it's more likely to find English speakers in PoA. Could you try both? If you have some spare time, that would be useful for long run plans, cos it would give you some notion of the country as a whole. They're both cities where it's easy to move around and relatively cheap.
As for Joinville, it's too small a city to get any traction. Stay in the capitals.
As for Joinville, it's too small a city to get any traction. Stay in the capitals.