Ed, congrats to the family. Pets are great for the family. Not only are they great companions but they can be part of many valuable lessons for the kids. Responsibility and respect for all living things are the first two to spring to mind but many other less obvious lessons will be learned.
I grew up around animals. Dogs, cats, guinea pigs, hamsters, fish. The house was always full of not just people but also animals. I think more than half of my childhood pictures have animals in them, mostly the dogs - especially Chelsea, a sable (think Lassie) Collie about the same age as me, and Tag, Chelsea's tri-color (black and white) daughter. This upbringing made me greatly respectful of all animals and all the responsibilities that go along with being an owner. It also ensured that I will likely never be without a pet in my home. I just couldn't imagine a home without a pet in it.
I'm sure you already know as a parent to take plenty of pictures of the kids. The same goes for the pets. I still regret not taking more pictures of Rocky, my first cat.