in the 15 months i've been an FO i've had 3 atco's on the jump seat. was a good time to swap idea's and to let them see how it all works at are end.
also as an FI i used to make a point of dragging my students up to the tower/ radar room. great experience for them and tended to make them less nevous when using the radio as they new it was just another person sat at the other end