While the idea of billions focusing their attention on Chicago sounds like a great proposition, I don't see the Olympics as the boon that politicians make it out to be. The Economist explains:
So how have the economics of the Olympics stacked up in the past? According to Holger Preuss, professor of sports economy and management in Cologne, all games over the past 30 years have turned an operational profit, unlike most other sporting events...It is investment, not operating costs, that cause the problems. Depending on what is already available, hosts may have to build new sports facilities and Olympic villages, expand airports, roads and public transport, and, in some cases, give their city centre a facelift. The hangover after the 17 days of Olympic glory can be unpleasant. Montreal, which made a profit on operations in 1976 but had to borrow heavily to cover investment in new facilities, is still repaying its Olympic debts today.
But I don't see concerns like that stopping Mayor Daley (and yes, if they got the bid for 2016, Daley will still be the Mayor) from having the opportunity to plaster his name around the city more.