I am looking into getting a Great Family dog. Please help! What breed would be good?

I am married with 2 kids and one on the way. Here in the next few months we are looking into getting a family dog. I have a few breeds in mind as I am a animal lover, but would like to get others thoughts. My husband and I have a 3 year old heeler who is a wonderful dog, but she treats us like her heard(that is what she is to do, they are working dogs) because of this she protects us with her life. I love the fact she would die trying to help my girls. This leads to problems as well. We would like to take her out to a park or just to pets mart and can not. So we would liek to find a dog that we can take running with us or nice wallks on days in the park. A dog that loves people and a good playmate for my girls. Plus a friend for a the dog we have and love now. Please help.