A case study of utopianism is available in Spencer Klaw's Without Sin: The Life and Death of the Oneida Community (New York: Penguin Books, c. 1993). This is a fascinating, carefully researched study of John Humphrey Noyes and his followers who sought to live out his "perfectionist" teachings. Noyes, like another religious prophet, Joseph Smith, came of age in upstate New York when it reverberated with religious revivals. Noyes sampled various expressions of evangelicalism, studied a bit at Andover, and floated around in "perfectionistic" circles incubated by (among others) Methodist preachers.
Noyes, however, could never tolerate structured settings other than his own. So, having thought through his views, especially concerning communal property and marriage, he launched his version of realized eschatology, the Kingdom of God fully established under his guidance. In time he recruited converts, many of them family and friends, and established a utopian community near Oneida, New York. Thoroughly communistic, the community eliminated private property--possessiveness equaled sin in Noyes' thought. Also abolished was monogamy. Thus Oneida is remembered for its "free love" milieu--though it was not quite as sex-saturated as university dormitories these days. To eliminate sin, Noyes believed you must eliminate possessive sex. Thus members of the community, with the permission of its elders, were allowed to have sex with anyone they desired. Since the sexes lived in different quarters, special rooms were constructed for their sexual liaisons.
As you might expect, Noyes himself was the primary beneficiary of such sexual freedom! Young women, needing the skilled hand of the master, were usually introduced to love-making by Noyes himself. Favored members of the community, interestingly enough, also received sexual advantages. Nevertheless, the community survived for 40 years before internal problems forced Noyes to flee to Canada and the remaining residents to transform Oneida into a prosperous business community.
What's interesting about this book, read in conjunction with Bryce Christensen's Utopia Against the Family, is the fact that the very things "advanced social thinkers" in our day espouse were tried by the Oneida folks. The traditional family was abandoned for such things as sexual liberty, day care for children, absolute equality of the sexes. When the Oneida experiment finally collapsed, there was an instant return to the traditional nuclear family. One suspects the same always happens simply because the family is as integral to the human condition as hearts and lungs. We can't last long without it!