If either or both of you are 62 or older you can use NW Senior Coupons. A booklet of four one-way coupons costs about $660. A roundtrip Phoenix to Brainerd would take two ticket... for a cost of about $330 per person.. $660 for both. Reservations must be made two weeks ahead... the coupons can be purchased anytime prior to flight (in booklets of four one-way coupons only).. and (I am pretty sure) Saturday night stays are not required.