Elegance is key at this semi-formal Black & White affair hosted by the venerable JW Marriott in Union Square. Imbibe on celebratory champagne and cocktails in the swanky downtown lux hotel as DJs spin Top 40, house, and old school cuts. And as the clock hits midnight, clink glasses to the event’s official mantra: “A toast to good music, good people, and good times.” The JW Marriott, 515 Mason St (nyeball.net). Dec 31, 8pm. $85 to $165.