The Seat Bid program on Spirit is a special service offered by the airline that allows travelers to bid for an upgrade to a premium seat after booking. If the bid is accepted, one can enjoy extra legroom and better seating without paying full price. The Spirit Airlines Seat Upgrade via Seat Bid is a flexible option that allows passengers to potentially enjoy premium seats at a lower cost. To avail more details related to the bid program, visit the official website of Spirit Airlines or read the blog at the mentioned link.