It sounds to me like good Rottweiler would be an excellent choice! They do not shed much and are most loyal and protective dog breed I have met! They are also active and fairly high energy ( but not excessively so), so I am sure they would love running and playing with your kids. They are also fairly docile in the home. They are also relatively easy to train because of their higher-than-average intelligence

There is also the fact that Rottweilers have a reputation for being excellent guard dogs, so it will also act as a deterrent for any would-be attackers.