Caution! Wearing a tie is not always a DCR5... here's a good example of where other less casual elements bring you down to DCR4 even with the tie. Still cool look.
Three Styles That Help You Stand Out No. 1: The New Slim, Trim Double-Breasted • If you want a double-breasted suit to look modern—and not like something from a gangster flick—keep it short and trim. And avoid Dick Tracy-grade shoulder pads, too. • Keep the jacket buttoned (including the interior button). It doesn't hang well when undone. • And unlike with single-breasted suits, go for a higher-cut six-button suit instead of a low-slung four-button model.
Best Mens Style for Spring 2013: Wear It Now: GQ
GQ's men's style guide infographic by Jake Gilchrist