We usually fly Delta from MN to WDW. They have the most direct flights and if you purchase wisely, fares are pretty comparable to the other airlines. Air Tran, Sun Country and now Spirit also fly out of MSP but we avoid using them due to limited service. Sisters did try Sun Country several years ago, but had a bad experience with them. Their flight had maintenance and cancelled. Not all airlines will transfer their passengers to another airline if the flight is cancelled, and you might have a substantial delay in departure waiting for an aircraft to be fixed. At least with DL if a flight gets cancelled, there are other options to get us there. January 2011 we were booked to fly nonstop on DL and a huge snowstorm was going to hit that day. DL precancelled all nonstop flights to MCO in preparation. We found out when we got to the airport about the cancellations...thought we were screwed! Nope! We were booked to Atlanta and first class seat there to MCO. Arrived at our resort at 11PM instead of noon, but we were there
Look at who the dominant carrier is going from your local airport. They might be your best bet for flexibility. If you go with another carrier with less service because they have a lower fare, bring a book in case there are delays