CHILDHOOD'S FUTURE by Richard Louv (Houghton Mifflin: $21.95; 410 pp.) . Trying to fathom why so many of the families he interviewed nationwide felt alienated, disconnected and out of balance, San Diego Union columnist Richard Louv capably chronicles all of the familiar problems of today's families, from overemployment of parents (leading to the "I'll play with you tomorrow" syndrome) to the isolating, numbing leisure of TV and computer games. But there are also some original insights into such trends as the decline in neighborhood interaction. Louv's solutions are generally tame--to mitigate the isolation of America's elderly, for example, he suggests that seniors sponsor essay contests for children.