Hi,
We went to the Duke State recognition ceremony yesterday so I'll report on what we experienced. DD was one of 13 5/6th Explore testers recognized and there were about 200? 7th graders. It was very much like a graduation ceremony, with a guest speaker and the kids being called by name to receive their award and shake hands. Our speaker was the NC teacher of the year and she was wonderful. She really spoke to the kids in a way that they could relate to. There were about 10 kids who were at the state ceremony who were recognized as also going to the grand ceremony. I know the TIP website mentions other activities going on for you that morning.
As far as dress, there was a wide range. Jeans, basketball shorts, t-shirts on a few and "casual Friday" pants and polos on many. A lot of the girls had on Sunday dresses and I think only one boy wore an actual suit.
I don't know how this compares to the grand ceremony (I hope to find out in 2 more years ;))but I would assume it would be similar. It was well worth the trip for DD to see all those smart kids together in one place.
Hope this helped.