I don't want to take away from the post, but the above statements bother me. How do you know what the average Marine is like? Are you implying they are all stupid? I spent over 4 years in the Marine Corps and found, for the most part, it reflected society well as far as intelligence levels. Some brilliant, some stupid, most somewhere in between.
Anyway, like others have said, the Marines have no medics. If your main priority is marketable job skills, look into the other services as well. I have no first hand knowledge, but it seems like the Air Force would be better for the sole purpose of after-military skills. I don't know what they have as far as medics, though.
You should also look into the Army, as well. It likely has the widest variety of jobs just by virtue of size.
Good luck to you.