I would recommend buff orpingtons or barred rocks. When I got my flock I wanted three things: docile/friendly birds, brown eggs, and cold hardy. So I started with two barred rocks for my backyard flock. They were great for a first flock. I had read that barred rocks were one of the breeds that start to lay at an early age-5 months. My barred rocks didn't disappoint me. They are very social and sweet and one started laying a week after turning of 5 months. The next spring I got two buff orpingtons to add to my flock. I think of them as the golden retriever of the chicken world. They're about the same color as my oldest golden retriever and have that same gentle disposition and LOVE to be with their people. However, they started laying much later than the barred rocks-8 months. It could have been the long cold spring that influenced that. Anyway, my buffs are very socially-interactive with people and always curious about what I'm doing. I do find that my barred rocks can be bossy to my buffs, but that could be that they are older and therefore higher in the pecking order.
I have a friend that has only buff orpingtons in her flock and they are wonderful with her young children. However, they had one of their chicks die because it was accidently handled too roughly by one of the youngest kids. Heartbreaking for the kid. So make sure you monitor young children with your chicks and flock. Teach them the proper way to handle chickens and interact with them. Don't assume they know how to be gentle. Having a family flock can be a wonderful opportunity for quality time and hours of entertainment as you watch and interact with the chickens. Plus it's just so darn exciting to go into the coop and find your own eggs for breakfast!
Good luck with your first flock. How exciting for your family.
I have a friend that has only buff orpingtons in her flock and they are wonderful with her young children. However, they had one of their chicks die because it was accidently handled too roughly by one of the youngest kids. Heartbreaking for the kid. So make sure you monitor young children with your chicks and flock. Teach them the proper way to handle chickens and interact with them. Don't assume they know how to be gentle. Having a family flock can be a wonderful opportunity for quality time and hours of entertainment as you watch and interact with the chickens. Plus it's just so darn exciting to go into the coop and find your own eggs for breakfast!

Good luck with your first flock. How exciting for your family.