Welcome to the CO Forum and to FlyerTalk, for that matter!

What's your goal in switching? If you're interested in upgrades, CO probably isn't the airline for you. If you normally fly full fare, like a full Y, then certainly consider CO. If you plan ahead, it can be easier to get an upgrade. Of course, if you tend to fly FC, I think that CO has the best domestic FC. (Though AA has an excellent business product on its B762's)

What routes do you normally fly? Aside from partner carriers (like Alaska!) CO doesn't offer much in the way of flights up and down the west coast.