The "other" great moment is photographing high school seniors I have know as babies or small children, and seeing how they have grown and matured. it is always an honor to tease them and see them smile in a whole new dimension some 10 years later.
The "next other" great moment is getting reacquainted with old friends who need senior portraits made for their student and they don't have time and they heard that "Tod does photography" and we get out and make some absolutely gorgeous images for them.
I think the best images come about when you are familiar with each other a little bit. I always like to shoot engagement photos for the engaged couples in advance of their weddings because it lets me see them in advance. I get to think about facial structure and the best lighting situations. I get to see them laugh and learn what makes them smile. I get to see where the flaws are in their features and how to hide them. And yes we all have some areas we see as flaws!
I still love doing this simply to get the opportunity to make something out of nothing. Where people start as a bundle of nerves and you keep working until you release the shutter on a relaxed smile and feel like you have done something for them that will last a couple lifetimes.