Keep also the Lord's Day

Re Reclaiming the Sabbath, by Gwyneth J. Whilsmith, January.
While I agree with Lynn M. Baab, that everyone, where possible, needs a full day for Sabbath, but not necessarily on Sunday. I would emphasize that wherever possible, it should be on a Sunday. While setting aside any one day for Sabbath may satisfy the needs of the individual for rest, listening to God, etc., if everyone has a different day, then the concept of the Lord's Day gets watered down considerably. It is much more honouring to God if we all celebrate it on the same day.
Besides, if everyone has a different day for Sabbath, what would happen to Sunday church services? What would happen to what remains of family life, if parents have a different day off from each other and their kids? The Lord didn't say to keep one day in seven holy: He said to keep the seventh day holy. It seems pretty clear to me that He meant it to be the same day each week.
While we are on the subject, how can Christians justify shopping and going to restaurants on Sunday, when it forces people to work on the Lord's Day? This blatantly contravenes the fourth of the Ten Commandments.