I almost exclusively fly Delta or a Delta partner ....almost 4 million miles. The product is much different. I would probably equate a big front seat on Spirit to American Airlines first class...complete with asshole FA's. What sets Delta apart is the customer service and the soft product. Far and away better than any other American flag carrier. Also...if you have a mechanical issue on a Spirit plane it could be a day or two until they run that route again..with the larger American carriers they have lots of options to get you where you need to be.Spirit also has first class size seats for an extra $160-200 RT cross country and works out to the same priced flight on Delta. No brainer.