I understand what you're saying. The letter does kill, and that is why I believe Sabbath should be kept in the spirit--though not necessarily each letter--of the Old Testament regulations. That is, do no unnecessary work on Sabbath, do not buy or sell, and keep it a day of rememberance and fellowship with God. Most SDAs do keep these OT regulations of how to keep the Sabbath. But context is taken into consideration, and Jesus' words about the Sabbath are also kept in view. "The Sabbath was made for man, not man for the Sabbath" (Mark 2:27), along with others.
As for the Sabbath no longer being binding, I believe that Jesus kept the Sabbath, that He rested on the Sabbath even in death along with His disciples (Luke 23:56), and that He never gave a command to change the law He had already established at Creation and written in stone at Mt. Sinai. The disciples may have gathered on Sunday, but there is no evidence of them making it the new day of worship.
Because of all the evidence of the Sabbath being a part of God's eternal law, I think that the sabbaths mentioned in Colossians 2:16-17 were part of the other feast days and ceremonies that were "a shadow of things to come," rather than an everlasting memorial of God's creative and redemptive power that was written in stone.