What is a large, intelligent and loyal dog breed?

As long as you are already considering a GSD, why not go for it? They are amazing dogs..Loyal, loving and certainly a great guard dog. Similar size and temperament to a dobie, so they would fit well together. (Or get another dobie)! My first dog was a GSD, I got her not knowing I was pregnant, so I had her 8 months before I had my daughter. Sheba was an amazing dog...never left my side while I had the baby..quiet, well behaved..and you could see the expression on her face whenever we would supervise play with her and the kids...such love. As long as you take the dog out for exercise, AND make sure you brush/groom often, there isno reason why a GSD wouldn't make a great indoor pet. And don't forget to do obedience and to socialize well with other people so that your dogs won't freak out when you entertain. Do right by the dog, and you will have a great friend for life.