TOM PERROTTAs thirtyish parents of young children are a varied and surprising bunch. Theres Todd, the handsome stay-at-home dad, dubbed The Prom King by the moms at the playground, and his wife, Kathy, a documentary filmmaker envious of the connection Todd has forged with their toddler son. And theres Sarah, a lapsed feminist surprised to find shes become a typical wife in a traditional marriage, and her husband, Richard, who is becoming more and more involved with an internet fantasy life than with his own wife and child.