Well, I'm wondering if you could take a place, like the Berry Center, and divide the rooms up into "genres". For point of reference, PAX had one MASSIVE room with tons of tables of all sizes that were available for anything. Check out a game, find an appropriately-sized table, sit down, play. You could potentially set aside one room for RPGs and spread games over multiple tables. Put enough distance between each table as to not have everyone drown each other out. I could potentially see a layout of "rooms" covering:
> Miniatures (Warhammer, etc.)
> Family Table Top Games
> Card games (Magic, etc.)
> Beta Testing (Game designers could showcase their games and run demos)
> LARP, etc. (One of the big hits at PAX was a pop-up group of people playing Johann Sebastian Joust, My son is in this video shot at PAX in January. It's a hell of a lot of fun.)
What's the thought on panels? I wouldn't envision inviting celebrities and stuff, but would there be a desire to maybe have a few panels for say, gaming-related discussions like "How to DM", "How to Write a Campaign", "Podcasting 101".... you know, stuff like that. You could set aside one room for that.
And heaven forbid I suggest actual live-play podcasting.
I'm trying to think of other venues that are more central and might accomodate.