Why would anyone with decent credit use a BofA Alaska Air VISA debit/check card instead of a BofA Alaska Air VISA credit card?

One word for me-- Costco. Costco doesn't accept Visa, except for gas. They only allow cash, check, AMEX or an ATM card for merchandise purchases. Since it seems we spend so much time there anyway, it made sense to add the debit card. Last month I earned 300 or so miles just for new pickup tires, which, with mounting, were priced better than anywhere else I had looked. Before this I would have had to just write a check and earn no miles.

cethen