Perhaps an adult dog from the shelter would be the best bet for you! That way you will have more an idea of the dog's size and temperament, and you could end up with a lovely dog and be saving a life at the same time!

You could also ask about how the candidate dogs get along with small dogs, which will be important with your two Chihuahuas!

A Golden or Lab could be a good dog for you after it is out of puppyhood, for example. A 5-year-old Lab is worlds different than a 5-month-old one! Same for Shepherds, and all of it varies dog to dog. I do not think most German Shepherds would be a good match, with your being gone for much of the day, but maybe the right one would be ...