I too was considering taking a year off between college and high school, but I'm glad I decided against it. I think that the American college experience is unique, and I wouldn't want to miss out on my freshman year. I'm probably going to take a year to live in S. America between college and grad school, but I think that right after high school few people have the maturity to take off and travel without a planned, structured program.
Also, your brother's achievements really should have no bearing on whether or not you take a year off. If you do, it should be for your own personal reasons.