Funny you should post this question now. I have spent the last week thinking about this very issue, and actually know exactly what will give you that look. However…I don’t know if you will like the answer!
You know that scene in The Karate Kid where Mr. Miyagi makes Ralph Macchio do all that “wax on, wax off” stuff? Yeah. It actually works.
I do a fair amount of upper-body work, including boxing with weighted gloves, but the only thing that has ever really given me truly awesome definition in the shoulders has been the two times in my life that I have had to spend 4-5 hours a day, for days on end, sanding the outside of my house. In my admittedly limited experience, the definition begins to show after about 3 days, and is pretty awesome after a week.
Maybe someone here will know of a workout that mimics that activity (holding a 2-3 lb. orbital sander out to the side at shoulder height, while pressing it forward against the surface of a wall, for a long, long, long, long time). Perhaps something along the lines of Tonique, but for the arms rather than the legs and butt?
Or you could get a job as a housepainter.