I feel a wee bit unpatriotic for saying so, but choosing Rio de Janeiro to host the 2016 Olympics was the right move, coming from an international relations angle.

Reasons why:

1st: South America has never hosted an Olympic games. Never. Just in the spirit of the Olympic movement's goals to promote world peace and equality, after more than a century of modern Olympics, it's time.

2nd: As WF points out in his essay below, American power and influence are waning, as is European power. When Europe held the majority of power in the world, it made sense to have the games there. When the US and the USSR dominated, it made sense to host in those countries and their allies (whether or not it made sense to boycott the opponent's games is another story). US hegemony post Soviet collapse deserved representation (see 3rd point, below). The rest of the world, the "global south" or however you want to phrase it, is gaining in economic power in absolute terms, which is translating to a gain in political power in relative terms. The IOC was smart in recognizing this.

3rd: The games have been in the West enough recently. Canada is hosting the 2010 Winter Olympics, London the 2012 Summer Olympics; the US just had the 2002 winter and 1996 summer games, and Australia hosted the 2004 Olympics. All told, that's 5 out of 10 (1996-2014) Olympics in Anglo/Western states. If the list is broadened to include continental Europe, the number is 7 or 8 out of 10 (depending on if you include Russia or not - 2014 host Sochi is kind of on the line between Europe and Asia). A Chicago 2016 Olympics would have tipped the scales in a decidedly Western favor, which is out of sync with the times.

4th: As the B in the BRIC countries, Brazil is widely recognized as an up-and-coming economic power. Just as China sought and deserved a chance to shine on the international stage (human rights violations very rarely have any actual impact on international relations), so does Brazil now deserve its chance. Russia is hosting in 2014, which just leaves I, India, which is preparing a bid for 2020 (in Delhi, which is also hosting the 2010 Commonwealth Games).

Part of me is a little sad that Chicago lost the bid - I live just 5 hours from the city, and have always wanted to go to the games. But who knows, maybe I'll get a chance to be in Brazil in 2016, or India in 2020, or South Africa in 2024.