I've never understood the sense in that Wright Agreement either Jim.
I already have my flight for my cruise in January but I did a comparison today between Delta and Southwest for my dates of January 9-14th. Southwest was about $382.90 and a comparative flight on Delta was $319.20. A $63.70 per person difference x 2 people = $127.40 total. I don't have to pay for luggage on Delta, but even if I paid $25 a bag for 2 bags ($50), I'd still be making out better on Delta. I can pack everything in a carry-on anyway. Also, I can pick my own seats with Delta. I've never liked the idea with Southwest of no seats and being put in A, B, or C, group for boarding. Of course you can get online early and print your boarding pass and hope to get in group A, or you can pay $10 for that privilege to be guaranteed Group A.
Bottom line is Southwest may or may not be a better deal depending what area you live. Do your comparisons. Just because a carrier calls themselves low cost, doesn't mean they are the lowest. Spirit Airlines is a good example, they say they are low cost, but charge for everything.