I've never been to a Unitarian service, but it's likely that my fiance and I are going to be married by a Unitarian lay minister this August. We're leaning that way because my boss (a Methodist pastor) told me that they would do whatever we liked, and as I'm a very liberal Christian and he is an agnostic, it sounded like a good middle ground to the both of us.
That said, I was raised by 1 atheist and 1 New Agey Lutheran. My dad, the atheist, insisted that we read holy texts beyond just the Bible. He wanted to ensure that we had a full picture of the spiritual world before we chose a path. Quite frankly, when I told him a number of years ago now that I was a Christian, he was shocked
I think this is because he did such a good job that I don't seem like I am (I think most people equate Christians with fundamentalist nutjobs; for me, it's mostly a label of convenience). I only went to church for a few years as a kid--3rd through 6th grade, and now I work for a church. I liked the church community as a kid, but it wasn't something that couldn't be easily replaced by Scouting or some other group.
The most important things you can do for your kids as they grow is to 1) urge them to explore and research, 2) encourage them to evaluate their own opinions, 3) ask questions about the world around them, 4) let them go to find their own faith or lack thereof as they get older, and 5) model a moral, ethical life without religion. I'm sure my dad wouldn't have agreed with many of the churches I went to as a high schooler (hey, I just wanted to hang out with friends, I knew they were crazy) but he let me go anyway. Further, because I knew my dad was a moral, ethical person without faith, I knew from a young age that one didn't need that external pressure of religion to be a good person.