You can actually get on standby using the web site check-in. I'm unsure exactly how you do it but I know this is something AS starting offering recently.

The easiest way to "poll" your chances is use seatcounter to check out how many seats are opened on the flight the day before, or you can start a new res on alaskaair (or another travel site) just to get to the point where you can see the seat map and check out how it looks

if you're gold you are priority standby, if it's just you I would say you have a very good chance of making your flight unless it's absolutely at its fullest (or oversold) but don't expect an upgrade

there are no standby fees, especially since you're gold

oh also, don't check in luggage, carryon