Don't agree with the above two posters.
Name of Hospital, Name of PI, # of Pubs matter enormously. Perhaps less so in med school apps, but they certainly have an effect. If I had a your choice, I would go for the one that has a big name, will give you good chance of getting Pubs. Of course, talking intelligently will matter, but you will be able to do that if you are involved in writing manuscripts!
As far as shadowing and exploring, they will require some effort regardless of where you are. If you have a decent personality, can get along with other people and aren't very shy, you can build relationships with in the department and explore your options.