As Partygoers Know, it isn't just the halls that get decked out come the year-end holidays. Our guy at left forsakes the penguin look of basic black tie by choosing a wool double-breasted dinner jacket with Lurex thread that's combined with a vest and wool formal trousers, all from Tiger of Sweden, $550; plus a wing-collar shirt, by Yves Saint Laurent for After Six, about $55; acetate/satin bow tie, by Stephen J. Sotnick, about $8; and sterling-silver-and-onyx cuff links, $170, and studs, $200, both by Alfred Dunhill of London. (His date's dress is by Marc Bouwer, Ltd., New York.) Above: The heavy swell at left makes strong fashion waves in a cotton pin-point dinner jacket, $300, and mohair/wool formal trousers, $125, both from Windsor European Fashion; silk/cashmere/lamb's-wool sweater vest, by Yves Saint Laurent Menswear, $110; wing-collar shirt, by Henry Grethel, $40; and silk paisley bow tie, by Alan Flusser, about $25. His martini-drinking mate likes a silk-blend woven jacket, $235, silk denim tweed slacks, $125, and a pleated cotton shirt, $55, all by Jhane Barnes II; plus a suede necktie, by Stephen J. Sotnick, about $20; and a diamond-and-yellow-gold tie tack, by Ivan Gregorovitch, $300. (The elegant object of their affection has on a dress by Marc Bouwer, Ltd., New York; her jewelry is by Vanessa Strougo, New York.) Right: The winning look of winter white--a wool smoking jacket and wool formal slacks, both by D. Cenci, $850; wing-collar striped shirt, by Lazo Shirts, $95; silk herringbone bow tie, by Vicky Davis, $10; and leather-and-rayon suspenders with brass clips/slides, by Alan Flusser, about $50. (The lady wears a dress by Robert Molnar, New York; gloves by Sachiko for La Crasia, New York; and jewelry by Eric Beamon, New York.)