Every major American city has the necessary infrastructure to handle a bid of this type on their own. Most have highly paid image consultants who help the city position itself for travel and tourism, as well. In contrast, Spain is about the size of Texas. A president of Spain is akin to a governor in real terms of population represented and GDP.
This is a job that can generally be handled adequately by locals. And, Chicago has plenty of local celebrities that are well-known on an international level that could have been tapped for this work. Further, this is a perfect role for a First Lady, not necessarily the chief executive.
It really is a matter of priorities, for me at least. We are a nation at war on two fronts. We are in the midst of the worst recession since the Great Depression. More Americans are out of work than have been at any point in the last 60 years. Our healthcare reform issues are not even close to being resolved.
If Obama doesn't see work for himself in the states that outranks traveling to Denmark in terms of importance, I could probably identify some for him.
In fact, I would go so far as to say that this is the FAIREST criticism I've see leveled at him so far, because it hits on the real priorities of what a President should be doing with his time/energy/budget.