Really? Midwest stuffy? Try Atlanta or the Northeast. Or even Los Angeles. That's stuffy.
Try open social interaction with random strangers in New England. Let me know how THAT goes.
I was going to say something like this, too. I've found the Midwest to be one of the friendlier areas in the country that I've been to, with the South being the only friendlier area I can think of right now. (Of course, I'm from the Midwest, so perhaps I'm a little biased.) The only exception to this that I've experienced is the western Pennsylvania area, and especially Erie. (No offense, Browntggr!) The times I've visited Erie recently, I think just about everyone I've met has been really unfriendly.
On the subject of high fives in line: one of my friends is a germaphobe, so I understand the aversion to high fiving random strangers. Like others have said, you're going to experience other people's germs at an amusement park whether you want to or not; people touch EVERYTHING there. Think about it. For me, it brightens my day a little to high five people, so I'm always down for a high five if someone offers.
Pennsylvania isn't in the Midwest.
BB7, who knows his geography.