Pat Robertson's CBN poses the question:

I think the true Sabbath is a day of rest -- one out of seven days. Jesus said, "The Sabbath was made for man, and not man for the Sabbath" (Mark 2:27). By that He meant that God has set up a cyclical type of existence for us, where it is absolutely imperative that we take a break in our work to rest, to be refreshed, to think of things of the Spirit, and to worship Him. Moslems celebrate Friday, Jews Saturday, and Christians Sunday. It is hard to say that one day has any benefit over another. The apostle Paul says in Colossians that we are not to be bound by any days. He tells us that we are not saved through the observance of Sabbath days or various feast days, because such things are just a shadow of the truth and the truth is Jesus Christ (Colossians 2:16-17). So in a sense we have a Sabbath rest in Jesus Christ all the time.

From a practical standpoint, I believe that people should read Isaiah 58 and see what it says about keeping the Sabbath. We should dedicate a day to the Lord, a day when we do not think our own thoughts or spend time in business or worldly pleasure but when we rest and meditate on Him. God says, in Isaiah 58, that if we do that, we will receive the heritage of Jacob and we will ride on the high places of the earth. That is a wonderful promise.

I have found that in my own life, taking a day off, which for me is Sunday, is a most welcome time. It is a time when I am not watching television or going to ball games or running around. Instead, I am seeking God. I am praying, I am studying, I am reading the Word, I am talking to the Lord, and I am being refreshed with rest. Setting aside one day a week for your Sabbath can make a tremendous difference in your life.

The reason Christians worship on Sunday instead of Saturday is that Sunday is the day of the Resurrection. Jesus rose from the grave on Sunday, and the Christian church celebrates that day. The early Jewish believers probably also kept Saturday as a rest day. Remember, however, that those who would be legalistic in this affair of literal Sabbath-keeping should stop work at sundown on Friday, observe complete rest, and not work again until sundown on Saturday. Frankly, I do not believe that Christians have to keep Jewish customs in order to please God. Jesus has fulfilled all the demands of the law so that His followers might live under grace (see Romans 6:15, Galatians 4:4-7). ― From the FAQ section of the CBN web site (now deleted).

Rome's Challenge to Protestants
Did the Apostles keep Sunday?
The Mark of the Beast and the Seal of God
Sunday is NOT the Sabbath!