Were it not for the arrangement between Delta and Alaska Airlines, I would probably have never found myself on Alaska. As it is, I end up in an Alaska Air seat semi-regularly.
There isn't much to complain about. The fleet feels very fresh, from the regional prop planes to their trademark 737s. The service in the air was well above average. All of the drinks are free, and they are constantly offering a new microbrew and wine from the northwest. All of that is capped off by an easy and smooth process on the ground from check-in to boarding. If my travel plans drop me somewhere on Alaska's route map, I definitely look to book on them first. They are well worth consideration if your travel plans do as well.
