I did work at the airport from 97 until mid 2002. After 9/11, most menus were practically cut in half because knives weren't allowed inside security. Eventually, I believe they were allowed back in, but carefully tracked and affixed to a counter by a chain or something. Metal knives aren't provided to diners, so no food that would require more than a plastic knife can be served.
Kitchens in the airport are insanely small, as food was generally an afterthought, and up until recently, was rarely prepared on premises. Furthermore, the incredible hassle of working at the airport (security mostly) can discourage people who can find work in a kitchen elsewhere. Keep in mind when eating the same dish at the airport location of a local favorite that they have less space, less equipment, and generally more hassle just getting to work every day that they would if they were at a street location.
If you don't mind having to go outside security but want to stay on premises, there's always overpriced food at Andiamo's in the Hilton attached to O'Hare. They had a Chicken Boursin with shoestring potatoes that was really delicious.
I don't think anyone is allowed on the roof anymore without serious security clearance. Everything is so closely monitored these days. Some things may have softened in the last two years, but I'm not totally sure anymore.
Midway's food court is no exception, but it was designed as a food court, and it wasn't in place of some crappy Host/Marriott concession (or run by them). The whole idea behind it (yes, I was on the team that developed it) was to have a sampling of the foods we have in Chicago, mostly Disadvantaged/Minority/Women-owned businesses. Often chains, but locally-owned, small chains. That's not to say that the big, national chains didn't propose inclusion, they just weren't selected.
I'll try to put together a comprehensive list (with better location descriptions), but since I no longer work there, I can only make suggestions based on older recollection. For clarification on my last post, "T" is for terminal, i.e. T3 = Terminal 3 (1,2,3 - domestic, 5 - international), and the letters are the concourse - B, C, E, F, G, H, K, L. T3 Main is the terminal building on terminal 3, right past security and not on a concourse.