Personally, I'm a bit biased toward American Airlines, having done most of my flying needs with them. Unfortunately with American, you'll likely have a layover at O'Hare.

If you're flying from Minneapolis/St. Paul, you can fly Southwest, but you'll have a layover at either Midway or Atlanta.

Other airlines available include Delta, United, and US Airways. There may be more but I'm not aware of them.

Hope the search goes well for you, and hope I am of assistance.