Looking To Find A Good Breed For A Household With A 3 Yr Old-preferably Medium-large To Large, But Not Huge!?

We had a house fire in oct/04 and lost our 2 cats & 2 dogs. We’re ready to have housepets again. It’s a no-brainer with the cats, but, we will be introducing my munchkin to dogs, since she is too young to remember the ones we had. I am curious as to what are good breeds to have with young children. The 2 dogs we had were very old and were not threats to the baby. One was a cocker spaniel, the other a golden retriever/daschund mix (imagine a retriever with 3 inch legs-he was just too cute!). I am a firm believer that children should grow up with a companion or two if at all possible, and I am ready to start over again with a new dog.
I will definitely be looking to adopt, and I am not sure if I want a puppy, or one that is grown and house-broken already.
We have also been investigating retired greyhounds, but they are kind of iffy with cats.
I will have to find something soon as this is an incentive for potty training that IS WORKING!!!
Do NOT want any small yippy yappy things!

Ideas For A Large Dog Who Is Getting Bored?

I own a 50lb greyhound/boxer mix who is fairly well behaved and in training to conquer the few things she struggles with (greeting people calmly). However, one issue we can’t seem to conquer is what seems to be her boredom. During the day she just lays around and sleeps a lot, but around 7:00pm she tends to get very wound up. Whines a lot, obviously wants us to play, and barks at us if we won’t play with her. However, when we play catch or anything else she gets quickly bored with it and wants something else. By the time she wants to move around (evening) we’re already exhauseted from the day. Any ideas on what we can do around the house to keep her occupied, or on how to make her more active during the day when we can play?