Holiday Letters, what do you write about?

[It's A Happy Day]

I have never done a holiday letter before but am thinking about starting one. I have several friends who live in other states and don't get to talk or see them as often as I would like. What do you all write in your letters & how do you put it? I don't want it to seem like a brag letter like I have heard people complain about I want it to be taken as a catch up this is whats going on instead of a "my kids are the best, cutest, noone out there is better than us letter."

Tips & helpful hints please...