That depends on what the bride has chosen to wear. If she’s in a formal gown, then the groom and all the men in the wedding party should be in tuxedos, with all the appropriate accoutrements. If she’s dressing a little less formally, a dark dressy suit is enough. If it’s a cottage or beach wedding, a tan linen suit looks great. Even if the venue is casual, a suit shows respect for the day, for the bride, and for the solemnity of the event.