If you are a very bright student, you can skip grade easily in Harvard. You can also take courses that is not your major, in case you suddenly feel interested in something else, say music. My friend is in Caltech, she is a 1yr student, taking courses that is for 2nd/3rd yr. In Harvard, you will meet real bright people, cos Harvard is more selective and have lots of scholarship to attract bright students around the world. They kick people out if they don't do well, while Cambridge seldom do this.