Here's my two bits: If it was me, I wouldn't travel. Travel when you're working - make living and vacation a part of your work career. My best travel times were when I was a teacher. Granted, you have tons of weeks off as a teacher, but you can rock your vacation like a pro when you're an adult and working, plus you have the money to do it. Don't get yourself in debt, especially credit card debt, when you're already in debt from school most likely. It's a lot more satisfying when you take a vacation where you can pay it off on your next credit card statement than if you rack up that debt and pay high interest for months (or years....don't do this).
If I was to rewind and take a year off between high school and college, I would find something that's in the field of study that I plan for college. I would go to a job in that field, and take any job you can, even if it's the janitor. Something that gets you in the building. Try to climb up to something in that time - meet the coworkers, see the environment. Maybe get two P/T jobs, one in a completely unrelated field that you're maybe on the fence about. That might steer your education to a major change, or even a double major. Who knows - you might find that you don't need the college experience, or you can keep this job part-time while in school and have a bright future ahead of you at that company when you graduate.
And if you do go to a four-year university and are off in the summer and are fortunate where you don't have to work...that's 4 summers of travel/volunteering/etc. you can do that equals a year off that you would have done.