You will not regret it. I've attended more than 30 Nationals and have always seen amazing items that you will never see anywhere else, including Cooperstown. And not just cards but trophies, uniforms, bats, gloves. In fact, I just wrote my monthly blog (shameless plug:
www.markearzoumanian.com and then click on "Love of the Hobby") about my many thrilling experiences attending the National. I'm biased but Chicago is a great town. If you decide to stay by the Rosemont Convention Center you can just hop on the Blue Line and be downtown in about 40 minutes. Bottom line: Go, spend the $$. You will say wow over and over again. Peace.