As someone who's currently ski-bumming or ski-semi-professionaling or whatever it is I'm doing, I'd tell you to perhaps wait it out. Grad school can wait in ways that a college degree cannot -- mostly because a satisfying life doesn't require post-graduate education. Should you find yourself enamored of the ski lifestyle after four years of college, you can sleep more easily knowing that you have x major and y GPA to place on your resume when you look to hop out of it. But if like so many folks you find that your several months prior to college have extended into more than a year, you'll find it more difficult to get back into the game. Best to fall behind later rather than sooner.
If it's all helpful, then, I'm 23 now, recently degreed from an East Coast liberal arts school after growing up in the Midwest, and have no earthly idea what exactly idea what I want to do with the next ten years of my life. I do know, however, that selling ski vacations isn't it. And at the same time, I know that I love the more immediate pleasures of chasing the hundred-day year and of ogling awesome gear on Tramdock. Perhaps this strikes you as ideal -- and perhaps it is.
But I caution you that ski bumming will change your worldview. The friends who surround you make your decisions regarding college, alcohol and drugs easier and more acceptable, I'd imagine. They support you and your values and shape your expectations. Leaving college, I also left my own support group of friends secure in their positions as management consultants and political analysts. These people had pushed me to excel, leaving me with the certainty that only a high score on the LSAT and an acceptance letter to a top-14 law school could lead to a fulfilling life. And just days into arriving in Summit County, I realized that, no, studying for the LSAT would not play a part in my winter plans. I had left my (obviously pretentious but still wonderful) group of friends for another set of folks with just as much passion an energy... for everything but career ambition and advancement.
I'm not saying, Euripides, that you will lose sight of your intended future -- in fact, I'd guess that a year in the mountains will bring it into better focus -- but rather that the people who come into your life will force you to reevaluate your priorities. We are social creatures after all and we play to the expectations of our peers. Right now the college path might seem like the most natural in the world, but when you find yourself surrounded by other intelligent people whom you respect and yet who have, oddly enough, made life decisions antithetical to those you would have made yourself just months ago, you begin to wonder if those plans you'd felt so certain about still make just as much sense as they once did. Get the degree first. Then, when yo can turn down career-track offers, do the ski bum thing. Best to keep your options open.
That said, if you do the ski bum thing, come to Summit County and work for Vail. Can't get much better than five mountains (plus Heavenly) all on one pass and within 45 minutes of each other.