Heather Mahar, a researcher at Harvard Law School, has been studying pre-nuptial agreements. She found, not surprisingly, that most people do not want to use them for fear of signaling (or causing) ambivalence about the marriage. Mahar thinks prenuptial agreements do comply with what economists think is rational, but not with the emotional commitments that most people value more highly.
Mahar does, though, think that premarital counseling should include a prenuptial checklist, so a couple can work through their common values about marriage, including what they think about divorce.
The most interesting part of Mahar's research to me was that some couples use prenups to establish higher standards for divorce than the low "no-fault" standards that most states use. Couples can specify the only grounds that they will allow for divorce, such as adultery, desertion, violence, or crime, and the distribution of assets that the guilty party must suffer as a result. Since many courts are unwilling to enforce the marriage contract itself, but instead allow unilateral divorce, strengthening the marriage contract through a personal pre-nuptial agreement might be worth doing.