One of the best comic conventions in America is Roger Price's Mid-Ohio Con, which occurs the weekend following Thanksgiving in Columbus, Ohio. The con is big enough that there's plenty to do, plenty to see, plenty to buy; not so big that you need two rest stops and an overnight stay to make it across the exhibit hall. I will be among the guests at this year's, which takes place November 30 and December 1.
Also present will be Sergio Aragonés, Al Feldstein, Len Wein, Marv Wolfman, Jeff Smith, Tony Isabella, Bob Ingersoll, and many, many more as you'll see when you visit the con website for more info. That address is www.midohiocon.com.