Well, for my 2 cents worth...
The best place to have this get together would be Chicago. It's got a huge airport close to the city, lots of hotels and transportation options, and there's a hell of a lot of stuff to do in the city. Oh yeah, and it's in the middle of the country!
I would be up for this provided the costs stay reasonable, but just so you know, I work for a hotel in RL, and this would not be cheap. Unless you can get half our server to commit with funds up front, you'd better not set your sights on a convention hall. You might be able to get a meeting room for about $300/day with some snacks provided but that's about it.
You should get this thread sticky'd since you're planning as far ahead as August. Keep in mind though that there are a lot of conventions and such that happen in that month. Good luck!