Thinking about this more, I would say that Collinsville is definitely "bigger" than Madison, around 50% more people in all categories. It's going to be Expanded this year though, so that will limit it some. It probably will still beat Dallas though I suspect.
Fort Wayne and now Milwaukee (formerly Madison) are so close in geography and time that I suspect they'll be smaller (500ish masters) unless there's a huge rush for points. I'd definitely consider going to both; Madison last year was nice, a little quieter than Collinsville but still pretty decent. Fort Wayne is run by the same people as Collinsville I believe.