Thanks, dickson and Siri. I think one of the issues here is emotion. Arguments are emotional, plans on how to handle disagreements between spouses are logical. So, it seems like you can make a decision with your spouse to not argue in front of the kids, but once the heat rises they can easily be forgotten.
Another issue to me is how we were raised, whether our parents shielded us from the worst of it, or just let it fly. What you said, Siri, about your parents taking each other aside and pointing out what their problems were is the sensible, logical, considerate thing to do. And, I don't have too much information to work with here, because mostly all I know is what I saw/heard as a kid, (ha, through three marriages I should say) how my wife and I handle these situations, and the little I've been told as far as how friends and family handle these situations--but I would venture a guess that most couples don't conduct themselves with such maturity. I will say that my wife and I have gotten a lot better over the years. Well, funny thing is, we had a long honeymoon phase, where we didn't argue at all. Then we hit a bad patch and couldn't carry on a conversation about nearly anything without arguing. Now, we rarely argue, and when we do, I tell the kids that their mother and I need to talk. So stay in your rooms for a while, and for God's sake, turn the music up!
I have an idea that's really no more than a hunch that we will often go against what we saw as kids. If our parents kept things hidden, if they rarely argued and if when they did they were not of the knockdown dragout variety, when we become parents ourselves we might feel that it isn't necessary to keep our arguments from them. But for a parent who grew up with their parents tearing each other apart right before their very eyes and ears, maybe they remember, actually can still feel, how they were affected by that, and so might go out of their way to never do that to their kids.