I had to make the exact same decision 4 years ago and I chose Duke. Based on the experience that I had there and the people that I met, I would do it again. The opportunities are all there and, as any other place, your experience is what you make it. Kay Singer, the pre med advisor is very helpful and an awesome person and she is unbelievably efficient when it comes down to applying to medical school. The BME major, however, is very demanding and a lot of people end up transfering into Trinity College and majoring in Bio or Chem. However, I have friends who have successfully completed it and were very happy about it. Durham is a MUCH smaller city and there is a lot less to do than in Philadelphia (I work at UPenn now, so I have lived in both places), on the other hand, I still feel that Duke (maybe because of size or perhaps bball) has more of a campus feel, more people live on campus and socialize on campus vs. at Penn where most live off campus. I remember that being the decisive factor for me. One more thing, I don't think that you should worry about your chances of getting into medical school at this point - I think that on that item the schools are pretty much equal and it really wouldn't make a difference in the outcome. I don't know much about the process at Penn but Duke has (as I mentioned before) an awesome advisor and excellent programs at Duke hospital (volunteering and shadowing - HCIP). Good luck with your decision! I think you will be satisfied either way!