I'm having trouble deciding between these two. I'd personalize it with kidlet's name and date of birth.
#1 - there is also an option for an all-silver version instead of two tone.
On the second one, I'd choose a different image (not a paw print) or a small birthstone gem, the second disc would have his date of birth, and the last disc would have his name (first and middle). Fonts are interchangeable, so don't pay attention to that part.
ETA: #3 This is the all-silver version of the tree necklace. I'm pretty sure you can get either version of the tree charm in it.
Which one do you like better? I can't decide!