I used the photo taken by the 'Santa people' as I did not pull out my camera once. My 3 yr old was having such a sweet conversation with Santa that I didn't want to miss one bit of it :)
After they took the typical 'smile for the camera' photos Addie began her conversation with Santa, telling him that she wanted a doll for Christmas. As I watched, I turned to the photographer & said 'you can snap a few of these'. Because what I saw right there told much more of the story than her sitting there smiling. It told the story of my sweet little girl who was more than thrilled to meet the big guy in red and tell him the one thing she really wanted for Christmas...all while sweetly holding his hand.
So I would encourage you to go for those unexpected shots. The ones when your kids aren't looking. Because sometimes those are the ones that will tell the story more than the posed ones!