On the way home, we were discussing this issue - particularly that the 4th commandment is perhaps treated the most lightly among conservative Christians. I just don't see us coming up with ways to explain away the commandments against adultery or stealing like we do for the 4th.
In thinking about this and studying the Scriptures, I think part of our lack of respect for the Sabbath is our lack of cultural influence. Our culture still generally values honesty and other "second table of the law" values. But the Sabbath is not. Stores and restaurants are open and there is little cultural influence to keep the day holy. We're used to and guided by that cultural influence so the lack of it in this area makes it difficult to see and follow the Biblical command.
I think we also (or at least for me) tend to think of our time in only two categries: work and pleasure. If I am not working (an easy to define time period) then I consider the rest of the time to be "mine" to spend with family or myself in entertainment or relaxation. I find I don't have a category for the time bounded by the Sabbath; it is not work (Exodus 20) or recreation (Isaiah 58).
So what is this time and how do we use it? I defer to the Westminster Larger Catechism:
Q. 117. How is the sabbath or the Lord’s day to be sanctified?But, I'm still not sure how to live that out in our family.
A. The sabbath or Lord’s day is to be sanctified by an holy resting all the day, not only from such works as are at all times sinful, but even from such worldly employments and recreations as are on other days lawful; and making it our delight to spend the whole time (except so much of it as is to be taken up in works of necessity and mercy) in the public and private exercises of God’s worship: and, to that end, we are to prepare our hearts, and with such foresight, diligence, and moderation, to dispose and seasonably dispatch our worldly business, that we may be the more free and fit for the duties of that day.