Y'know, I think those three should have had their own spin off series, like "The Adventures of Ducky, Spike and Petrie" or something like that. They just are a really good team those three.
I have a headcannon thing that Petrie can have an A-type personality if he's given the chance, so he would be the insecure alpha of the group, but Ducky would take an ineshitive(sp?) if she saw fit for the situation. Spike of course would be the gentle, understanding, but strong silent protector of the group, since he's the largest one of the three.
Anyway, I'm going off on a tangent here, but your photos made me think about that.
I unfortunately do not have images, but when I have more time, I'd like to talk about my favorite scenes with certain characters.