That's great! Dogs and their chemistry with other dogs is so funny. I suppose they're just like people to a certain extent - some become best of friends and others just don't sit well with each other.
It's hard to read your description of your two dogs without a smile on your face. I'm a dog lover for life, but at the moment don't have any in my life.
Friends of mine that have a baby on the way are thinking of giving away their mastiff/lab cross (which they bring with them every time they come over as they know how much I like her) and I'm seriously considering adopting her. It would be a win/win for both of us but I'm a little hesitant to make the commitment. It would definitely force me to come home for lunch (which would get me out for an hour or so and would be a good break from the daily chaos) and to get outside more, but I still don't want to commit to it unless I'm 100% sure it's the best option for her. She's a great dog and is well trained and well behaved, but being responsible 24/7 for her is a whole other story. I've seen too many people (personally and online) that shouldn't be dog owners and I would hate to be even remotely like them, although I know I would never neglect an animal. There are some sacrifices involved in owning a dog, as you obviously know, and selfishly enough I'm not 100% sure I can commit to making them. I like being able to get away to go fishing or on road trips as I please and there would be some careful planning involved if I added a dog to the equation.
Anyways, I digress.
Congratulations on the new family member!