I just got back from a ORD-GRU (and back) run this week. I flew C on the way down and Y (upgrade didn't clear) on the way back. Crew was great on both legs. I love the fact that UA blocks middle seats. It was quite comfortable in Y! on a 767 with the middle seat open.

GRU's international terminal is not very nice. It's quite small and there is only one place to purchase food/beverage. You'll be very happy with RCC access there. The RCC is nice, but it was pretty crowded when I was there. As for outside the terminals, there is a fair amount of shopping, restaurants, etc. I was not in the GRU domestic terminal at all. That said, security is very different for domestic connections. They don't require you to remove your laptop from your bag or take your shoes off (yeah!) as such, you can clear security pretty quickly. Clearing immigration when landing in GRU was slow for non-Brazilian residents.

As for yellow fever, I did not get vaccinated (oops?). It's usually only in the tropical regions where you are at risk, and the coastal cities are usually exempt. http://wwwn.cdc.gov/travel/yellowBoo...llowFever.aspx has a map. As you will see, PAO is not considered an endemic risk area.

I've been to both Bolivia and Peru (in risk areas) and never had a problem going to other countries since then (EU, Japan, Australia, NZ, etc.). I think they only tend to bother you if you are coming directly from an at risk country.

Enjoy Brazil, I had a great time.

Make sure to get a visa if you need one, the process is slow and its a pain.