Glittery, gabby Manhattan love-and-work hassles--as three 30-ish career women share a 12th St. brownstone and eye the tradeoffs involved in opting for independence as opposed to marriage and motherhood. Blonde and beautiful, cool Cass Campbell from Seattle loves the admiration of men both in public and in bed; but the greatest thrills come from coups in her top-level spot at an ad agency. Then there's lawyer Paula Gabriel--""earthy, ethnic, kind""--who will argue an abortion case before the Supreme Court. And the last to share Cass' brownstone--nicknamed ""Casita Rosita""--will be writer Ellin Barnett, divorced from Hollywood actor Tony, and mother of teen-age Lara (who is happily settled in with Tony on the Coast). Soon, then, there's a veritable rush-hour of men bringing problems. Cass moves to a rampagingly acquisitive corporation, determined to make VP--and possibly also the top honcho, sleek (but humiliating) Grey Turner. . . while magazine impresario Nick Pappas suggests marriage (but somehow for Cass it's not worth the bi-coastal effort). Paula, who bravely offers a cry-on shoulder to pal Max Morton when he's desperately in love with a kid named Susan Starflower, finds herself booby-trapped by passion for an old flame--exploitative Jake, who's just surfacing after ten years underground because of a campus bombing. . . and dumps Paula after blackmailing a Kennedy-style senator. And Ellin successfully peddles articles while working on the Book--but Tony will die, leaving Lara, crises, and a dilemma: motherhood and responsibility vs. freedom. So, finally: the many individual squalls rock the boat of the three women's friendship; their final trade-offs will tri-sect the household; but Casita Rosita's bastion of female empathy (both helped and hindered by a male stud in the rented basement) proves to have a solid foundation. Complete with energetic sex, posh-to-trendy settings, and the compulsory Lib/communion scene (women ""validating each other""): flashy suds and one more time around a familiar cycle.