I watched both presentations and here are a few thoughts, based on my expereinces of work for both Atlanta's Olympic Bid and an employee for ACOG.
Rio's bid felt like a sincere plea to bring the Olympics to the City. Rio communicated that the Olympics would be bringing something to the city that didn't already exist. Chicago's seemed like a presentation to show that "Here we are" Come bask in our perfection. When Atlanta was bidding with other American cities, San Fransisco's presentation seemed to say, if you want to bring the Olympics to our great city, here is a list of things the Olympics will have to do before we will deem you worthy of how amazing city and people. If you truly want something you need to put it all on the line.
Rio stayed positive though out. Right at the beginning of it's presentation, Chicago had to bring up the racism of America past in it's reference to Jesse Owens.
Rio's passion felt real through out to presentation, Chicago was as very business like, even the attempts at inspiration seemed passionless.
Chicago's presentation also made a fatal error. It said that we know the Olympics are about the Athlete. WRONG! After the Atlanta games, Carl Lewis was asked about is experience at the Games and to respond the apparent snub that Samaranch made when he state that the Atlanta Games were "Most Exceptional" rather than "Best Ever" that he bestowed on his hometown of Barcelona. Carl started that he and all the Athletes he'd taked to said that Atlanta had be the best run as for as they were concerned. But he added that AGOC's mistake in the eyes of the putting the Athletes and the Spectators first, when in the eyes of the IOC is is the IOC, the NOC's, and the Sport Federations, that should be the center of ACOG's effort.
Rio put it all on the line, just like Atlanta did.
I will pass on a mention of the Obama effect. There is no one on this site that is interested in honest thoughtful discussion about anything concerning Obama.