Writing as a Southern Baptist girl who followed the letter and spirit of the "wait until marriage" law, I can tell you it's no guarantee of anything. I could not in good conscience advise the three children of that marriage to wait until the wedding night with their prospective life partners. I'm not sorry I married their father, because I am happy to have those particular children in my life. But I knew from the first night, in a way that spelled doom, I had married a selfish person who did not understand the idea of caring fully for another person. I learned that my fear of being "too" sexual had drawn me into a marriage with someone who did not desire me particularly. And the selfishness and the lack of particular desire in dialogue with my own rigid sense of what was right and proper and my judgment on both him and myself made for a very, very unhappy marriage and his eventual departure for what he imagined would be a happier life. 
Oddly enough, once I grieved fully the loss of the life I knew to be "right," I learned to be happy. And eventually I fell in love and had the courage to get married again, to a person I knew could care for others and who found me particularly, well, desirable. What a relief! 
We don't live in a time when the culture demands and nearly guarantees that marriages will be stable and people will have time to work through their difficulties. The same loosening of laws that protects women from being treated as property also allows the less committed among us to take a walk. And whether we like it or not, that is the world in which our children live. Here's what I want for mine (who are 23, 18 and 14 now). I want them to view themselves as whole people, loved body and soul by God. I want them to love themselves, body and soul, and to recognize how inextricable those two parts are. I want them to love another person, body and soul, and to regard that person's wholeness to be as precious as their own. In talking to them, I've called it a Love Ethic where sex is concerned. Love yourself, love your partner, and remember that how you live is an expression of how you love God. It's for them to work out when that happens, and I trust them to be true to their teaching.