I believe that it does open on the 9th for keynote speeches, addresses, meeting, etc. but the real fun doesn't start until the floor opens on the 10th. We'll be there.
I have gone for the past 5 years, and while it can be exciting, I gain a lot more information, and see a lot more games when I am at home reading the news sites. Not to say that I don't enjoy going, or that going lacks benefits, but it sure is tiring.