Here is a link to the Train Festival in Rock Island, IL July 28-31. It looks like a pretty big deal with eight locos under steam, exhibits, train rides, paddle wheeler rides and all sorts of stuff. I looked at some of the ticket prices and they seem reasonable unless you want the swank accomodations in the Milwaukee Skytop observation for a fan trip. But it's a good location in the middle of the country, on or near several freeways, and in an area which isn't terribly expensive. (I know that because I went to college there a couple of hundred years ago.)
-- D