First off, WELCOME to Pet Talk!! You've come to the great place!
A Lab would have been my first suggestion, so the Choc lab you are talking about may just be the answer you're looking for!
I too would worry about a Herding dog being to snippy with small children. A herding dog's instincts to herd start with nipping the heels of what they are herding.
Any dog can learn anything as long as you take the time to teach them! Dogs are eager to learn new things and most look for a job to do and you'd tend to have less behavioral problems with a dog that has a job!
Good Luck!