I stand corrected. My copy of Trade Show Executive arrived today and in it was their annual "Gold 100" of top trade shows.
NACS is number 52. I had my stats wrong.
The show typically over 380,000 square feet of exhibition space, it does move between cities (rotating through Chicago, but including Atlanta and Orlando). There are almost 1,400 exhibitors and the attendance typically is over 22,000 over the three days of the show.
I'll learn more first hand starting tomorrow.