This is pretty well laid out, but I'd have to say the navy is better at keeping families together. I know when we were in Korea, the navy was the only service there that didn't seem to have issues with bringing dependents.
I will agree that if you want to see the world, go Navy! We have been so lucky to see all that we have, lived on three continents and have had a blast--all this while married. Although there are a few exceptions, navy bases are usually on the beach too, and not the middle of nowhere.
To answer the orginial questions, we're on both sides of the coin. DH is both military (as a reservist) and a civilian, but we live overseas in the military community. When we were between military jobs, working in the states, that was the hardest time in our lives. The military has been able to provide us so much more in the way of benefits and security (job, financial, etc.) than the civilian world ever did.
I had a vague idea what I was getting into when we got married, but it's still been a roller coaster, although a fun one! My kids love all the benefits we've received being military, including all the traveling. That is the one thing they mention first when asked what they like most, that they get to travel.
Wishing your son and you all the best in your decision. I guess for us, it has never been a question of what service to join, both my dad and Dh's parents are navy. That's where our ties were, wouldn't have thought about going army or af. LOL!