International business office location for South America

We want to set up an office in South America and am looking for suggestions on locations. We have offices in Dubai and Hong Kong. So please use those as a comparison.

From Dubai, we can get to anywhere in the ME, Africa and Central Asia. Hong Kong lets us into the rest of Asia and the Pacific. Each of those cities has great infrastructure, is US friendly and have good economies in their own right.

Thanks for the thoughts!