Because these are considerations that shape many a noble ambition, here’s the nut of my reply.
How do you want people to feel?
I’m speaking of everyone who participates in the Fair in whatever ways they do: guests, musicians, vendors, even those who may never attend the fair but only hear of it somehow––not to mention the steering committee itself.
As you and your pals get increasingly clear about how you want people to feel about the Fair, then the question becomes what does it take to create that feeling in all the Fair’s distinct parts: from the website, to how musicians are managed, to the quality and presentation of food, to how clean and beautiful the site is maintained, to...?
Memory is funny thing. A year later, my guess is, most folks won’t remember a whole lot of specifics about the Fair, but they will remember how they felt. And that may be their primary reason for attending again, or saying a kind word about it to someone.
The feeling you wish to elicit is the purpose of the Fair. Everything exists in service of that purpose. This isn't at all an unusual perspective. Last I knew, the purpose of the Disney Company was "To make people happy."