I've never been impressed with the Expo Center. The last one was more like a yard sale than a gun show....bits and pieces of private collections, very litttle rhyme or reason behind many of the tables' contents, and minimal variety in dealers.
If you can get past the beef jerky and jewelry at the Convention Center, there's a broader range of dealers, plus some guys dealing in volume (ammo, magazines, etc.).
I guess it depends on whether you're looking for a specific item and want to maximize your chances of finding it, or if you want to paw through who-knows-what and maybe find a treasure.
"To spit on your hands and lower the pike; to stand fast over the body of Leonidas the King; to be rear guard at Kunu-Ri; to stand and be still to the Birkenhead Drill; these are not rational acts. They are often merely necessary." Pournelle