Business Aspect

Hello, we are from NY coming to Chicago for a quick visit this summer. Its the bacis "travel to a new city, see tourist attractions, take pics, go home". But, I wanted to know, how does Chicago stand amongst the "Big 5" of the world? (Being NY, London, Paris, Tokyo, Hong Kong) Standing in terms of business/finance, company HQ's etc etc. Are there any business website sthat show how diff. cities stack up? Thanks! (Also, anything in Chicago we SHOULD NOT MISS? We'll be in April 11-14) >