I agree with doing both sub-I's to see which you like better. You can always drop one if you make up your mind before then. If you're still not sure after your sub-I's, you can always apply to both fields and decide as you go through the interview process and take more electives. I had a friend who did this with family med and peds and it worked out fine. She simply had to interview at more places than she might have liked, and had to have two versions of the personal statements and LOR's. As she interviewed and spoke with more people and saw more of what is done at each program she felt very strongly she was making the right choice for her in choosing peds. Don't worry--you'll get there! Don't listen to deans, etc telling you that you MUST decide ASAP. It's a little easier to, but it's fine to be unsure right up to the day you enter your rank order list as long as you present yourself as being sure at interviews and in your personal statement.
