Trading Up, which is almost exclusively about different ways of going down (written pseudonymously and proficiently by a woman (?) of other kinds of book experience), is intended no doubt to replace the late and far more puritanical Miss Susann. You know the plot by rotation: Dilly who finally proves to be ""rock-solid"" after ""revirginizing"" herself for an older man; ambitious Glynnis who achieves another kind of rock solidity -- the diamonds of a Lord Burke; and mostly Jana, poor Jana, through her marriages to a stockbroker, then a gross character who sets her up for adultery before brutalizing her horribly, then Michael--the man she really loves-who is only up for sex before marriage, and finally an unsatisfactory affair with a younger painter. Jana, you can anticipate from the formula, has nothing more to live for. . . . The demises-eh-scene include New York, East Hampton, London and California and the book is all too obviously for the woman whose consciousness never cleared her pudendum.