I am on our local county fair board and I also judge other fairs in Open Class and 4-H. First of all thank you for entering. I hear so many people say that there is nothing to look at and at the same time find out that they do not enter anything. If you want a fair, people need to enter items.
I don't know your categories and rules so here are a few ideas: a classic from scratch Angel Food cake, chiffon cake, any flavor of a layer cake, petit fours.
Good luck and thank you for entering.