Chicago is a huge show and will be very busy. Make sure that you test drive all the machines that you are interested in.
Are you interesting in a sewing machine or a quilting machine ? There is a difference. I can quilt on my sewing machine but it's not the optimum way to quilt. I can make a quilt on a longarm, but boy it sure can quilt.
If you are looking for a quilting machine take a look here
http://www.quiltingboard.com/posts/list/18992.page It should help you to ask the right questions and give you some things to look for.