I would keep the secretary one. In the three years you were an MA you didn't get to work closely with a physician? I was an MA and was in the room all the time! Great experience.
I don't know much about being a scribe...other than I see them pushing computer carts all around the ER. See if you can set up a once a week thing with one of the physicians you work with. Just ask, "hey do you ever let pre-med students shadow you?" Most of the time they say yes, or will refer you to someone they know who is "better for that kind of thing."