Look into Black Lab's.
Very protective, loves kids.
Extremly smart dogs. You can teach them anything.
The one we have is so attached to my wife, it is almost like he is her shadow.
We keep ours in the house, he does not shed much, and is trained to hold "his business" for over 9-10 hrs while we are at work.
When the grand kids come over all he does is watch over them and make sure nothing happens.
He knows the difference in how to play with 3-4 yr old kids vs the 16 month old one that have just started walking real good.
If somebody rings the front door bell his is right at it barking, teeth showing, and hair raised up on his back.
After he realizes it is somebody knows the tail starts wagging, and he wants petted.