I got a German Shepard for my son, he's 3 in November. The two of them are inseparable, they play ball take each other for walks (mostly the dog takes my son!) lessons are key and we've been doing lessons since she was 8 weeks old. We got her while we were still in our flat and knew we were moving so house training was tough but she soon learn't what outside was.
Now that we have a garden she roams around and its definitely a warning to anyone wanting to stop in for an unscheduled visit. I grew up with a Border Collie, but they needed more exercise from what I read and the German Shepard was my next choice.
Yes she has munched the couch a little here and there, but if you have a 3 year old you'll be used to the crumbs, sticky walls and all the wonderful things that come with kids! After all she is still a kid herself! The second photo always reminds me of the truth about pets...