You are too early in your college career to limit yourself to Harvard and Sloan. First decide what you want to do and then make a decision. If you want to be a young CEO immediately out of college with a small to medium sized business go to Harvard or UMass. If you want to get into international business go to Thunderbird (yes, its legit and an excellent school). If you want to become an executive right out of college go to Northwestern. While having a plan is necessary make sure your decisions are well informed and legit, and maybe they are and you have already decided what you want to do in which case good for you and I hope you get in to either Harvard or Sloan. But otherwise you are inhibiting yourself. I am going to be graduating soon and I have changed my major twice and changed my desired career paths over and over again. However, all of these changes have still been within my original goals.
Also realize that these elite schools are looking for work experience. If you can get in while you are in school than great, if not than get a good job for a year or two. Realize that every legit applicant to these schools already has a great GPA and high GMAT scores and even lots of extra curriculars with relevant organizations. These things do not make you unique. It all comes down to two things: what you know and who you know. During my college years I have tried to develop both of these things. Don't just look for the great internships. I am studying Entrepreneurial Management. To build my resume` I have been independently consulting small businesses for free. This accomplishes three things: Builds my network, creates great references, and gives me the necessary experience. I am even working with an angel investor to start a small business of my own to get even more experience. I would recommend you do similar things that apply to your major or what you want to do. Sure, I have no time for myself and get very little sleep, but who sleep's in college anyways? If you want to read more I actually was blogging about this yesterday here
Resume` Building.
Anyways, sorry if the answer was lengthy I just feel passionately that a lot of business students are hurting themselves by not realizing that it is more than an education and good GPA you need to truly reach your potential. Good Luck and if you have anymore questions just ask here or comment on my blog.