Hey JCYL,
I am currently doing a Doris Duke at Iowa and I would say prior to beginning I was much like you in that I too leaned towards clinical research. It is true that you might be able to pump out a few clinical papers quickly but they will most likely be case reports that could be done as a medical student without taking time off. Strong clinical papers require lots of statistical analysis that usually means doing chart reviews of several years of patient samples that just doesn't seem as worthwhile if you are doing a full year of research. Plus in many peoples eyes a basic paper is worth much more than 2-3 short clinical papers. And, as a clinician, if you decided to stay academic, clinical research will be inherent to your practice.
Having never had any basic science experience I used this year to immerse myself into the laboratory (basic science genetics) and was able to master relatively simple techniques very quickly (i.e. PCR, Direct sequencing, DHPLC). I recommend going this route and picking a lab that is big enough where you can learn from postdocs as well as your PI because needless to say you will probably be last on your PI's list of priorities and having others to answer questions that your PI need not worry about is very helpful.
If you are going to take a year off my advice is to do something that you probably cannot do during your career as a fulltime medical student and make yourself more marketable in terms of securing a residency position.
Lastly, and I will get off my soapbox now, working in basic science has really taught me to approach problems differently than I think I did in my clinical years. This is probably the most important thing I will take away from the year and I think is something you should really strive for.
Best of luck,
Amit