I think I found a great rate from Michigan to Disney on Delta but I'm not familiar with them
Out of Michigan, Delta Air Lines is usually the airline that was formerly known as Northwest Airlines. In 2008, Delta and Northwest merged. The Northwest name went away completely on January 31, 2010.
Delta operates pretty much like the other remaining legacy carriers (American, United, U.S. Airways, and Continental). That means free advance seat assignments, 2-class service on most aircraft, food and alcohol for sale in economy, free non-alcoholic beverages, flights available for booking 11 months out, schedule adjustments that can cause your flights to change, charges for checked baggage, and HEAVY-DUTY PENALTIES IF YOU NEED TO CHANGE YOUR TICKETS.
I put the final item above in upper case because people tend to overlook it in their quest for the lowest fare. If you need to reschedule your flights, the fare rules for discounted tickets on legacy carriers normally require you to pay a $150 change fee plus any fare difference PER PASSENGER. It doesn't matter if there's an illness, family emergency, crisis at work, issue at your destination, or other good reason to change. The airline expects you to pay $150 to retain the value of your tickets toward new tickets. The airline benefits if you have an emergency. READ AND KNOW THE FARE RULES BEFORE YOU BUY. You can mitigate the risk somewhat with
travel insurance, but there are limits to what's covered.
In comparison, Southwest applies the full value of your current ticket toward a new ticket, without a change fee. That's worth a lot. And Southwest doesn't charge for checked luggage. That's worth a lot too.
The lowest price isn't always the lowest price.