How do Protestants keep the Sabbath? Exodus 20:9–11 (ESV)
  Six days you shall labor, and do all your work, but the seventh day is
  a Sabbath to the LORD your God. On it you shall not do any work, you,
  or your son, or your daughter, your male servant, or your female
  servant, or your livestock, or the sojourner who is within your gates.
  For in six days the LORD made heaven and earth, the sea, and all that
  is in them, and rested on the seventh day. Therefore the LORD blessed
  the Sabbath day and made it holy.


What is an overview of Protestant views on the Sabbath?

(Caveat: I'm not interested in the Seventh Day Adventist position.)
Within Protestantism there are many views regarding the proper way to keep the Sabbath, even among those who generally agree that Sunday is the most appropriate day to observe it.  I'll provide a brief overview of three of the main views: Spiritual Sabbath, Continental Sabbath, and Puritan Sabbath.
Spiritual Sabbath
This view is held by many Protestants across denominational lines, particularly among those influenced by dispensational theology.  Proponents of this view, such as Michael G. Moriarty, argue that the Sabbath is not a creation ordinance; that is, God resting on the seventh day of creation was not meant to be a binding law on all humanity.  Instead, it first appears as a command in the Ten Commandments.  Defenders of the Spiritual Sabbath contend that passages like Hebrews 4, which refer to an eternal Sabbath rest, and Christ's claim to be &quot;Lord of the Sabbath&quot; (Matthew 12:8) indicate that Christ is the fulfillment of the Sabbath decree:

Jesus Christ is the eternal Sabbath rest. [...] When we trust in Christ alone we close the doors to works-righteousness and enter God's rest.  By our spiritual union with Christ, &quot;we are already living in the seventh day, the eternal Sabbath of God.&quot;

Proponents of this view, holding that &quot;every day is a Sabbath,&quot; suggest that &quot;finding sufficient rest every day&quot; can be seen as an implication of the New Testament Sabbath.  They also argue that weekly corporate worship is essential, citing Hebrews 10:24–25, but may not tie this requirement specifically to Sabbath-keeping.  Furthermore, recreation and other activities are permissible on the Lord's Day, as long as corporate worship is not neglected.
Continental Sabbath
The Continental Sabbath view, expressed by John Calvin and the Three Forms of Unity, sees two primary purposes of the command: ceremonial and moral.  The ceremonial purpose, proponents say, has been fulfilled in Christ, and thus the Sunday Sabbath, in and of itself, is not a divine institution.  However, the moral purpose remains, and requires us to set aside a day for corporate worship and rest from ordinary labor.  The choice of a seven-day cycle, with Sunday the designated day, is a practical matter, not a divine decree.  Recreation, so long as it does not hinder worship, is permissible.  The view is summarized well in the Heidelberg Catechism:

Q. What is God’s will for you in the fourth commandment?
A. First, that the gospel ministry and education for it be maintained, and that, especially on the festive day of rest,
I diligently attend the assembly of God’s people to learn what God’s Word teaches, to participate in the sacraments, to pray to God publicly, and to bring Christian offerings for the poor.
Second, that every day of my life I rest from my evil ways, let the Lord work in me through his Spirit, and so begin in this life the eternal Sabbath.

A number of denominations maintain a variant of this as their official view, such as the United Methodists and Southern Baptists.  Some denominations specifically hold to the Three Forms of Unity, such as the Christian Reformed Church.
Puritan Sabbath
The Puritan Sabbath view is most comprehensively expressed in the Westminster Standards and is primarily held in conservative Presbyterian denominations like the PCA and RPCNA. It holds that the Sabbath is a creation ordinance (Genesis 2:2–3, cf. Exodus 20:11), and continues through both Old and New Testament periods, with the only change being that the day of its observance changes from the seventh day to the first day.  It is a &quot;positive, moral, and perpetual commandment binding all men in all ages&quot; (WCF, 21.7).
On that day, people are to turn from &quot;their own works, words, and thoughts about their worldly employments and recreations&quot; (WCF, 21.8) and instead devote the day to holy rest:

The sabbath or Lord's day is to be sanctified by an holy resting all the day, [...] 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 exercise of God's worship. (WLC, A. 117)


References

Frame, John, The Doctrine of Christian Life (2008), 516–27
Moriarty, The Perfect 10 (1999), 94–104