Tom,

With regard to Calvin, Pilgrim has I think given a satisfactory response. I would add that I think it possible that Calvin's views on the Sabbath may have changed in the course of his life towards a "Sabbatarian" view, thus some of the confusion on his actual position. As for Luther, he was by no means a strict Sabbatarian - he thought a day should be set aside, & since due to ancient custom Sunday had been set aside, then there was no reason to disrupt that order of things; but he did not believe that any particular day of the week was to be regarded as the Sabbath day. You can read a sermon of Luther's on the subject here.

Kyle

I tell you, this man went down to his house justified.