With its New Age piano soundtrack and lengthy scenes of apparently aimless chitchat, Sisters frequently seems like a soft-headed version of thirtysomething. ... But on its own terms, Sisters has a lot going for it. Its simple premise — following the relationships among women ranging in age from their mid-20s to their late 30s — is a terrific idea. And the actresses immediately establish an engrossing contrast in styles, from Kurtz's subtle wryness to Phillips' blank-eyed unknowability.