Short answer
The rule: same register, ascending detail. The groom’s garment is distinguished by cloth depth, making quality or one quiet mark — not by brightness or a costume-y contrast. The best man sits one deliberate step beside; groomsmen one consistent step behind. Nobody wears novelty: the photographs hold these people for decades.
The hierarchy that works
The groom can set the formality and palette. The best man and groomsmen can follow the same register with details that suit their budgets and preferences. If one outfit is commissioned, ask the maker to confirm its fitting and delivery plan; it need not dictate the service chosen by everyone else.
The coordination conversation
Practical order: groom’s cloth first, party palette second, budget conversation third — openly. A good house helps set the party’s register as part of the groom’s commission; grouping party fittings where windows allow is part of the planning (see the timeline). What never works: deciding each man separately and hoping.
The “says yes to the suit” problem
Novelty waistcoats, mismatched Hire-shop greens, costume contrasts: every generation has its photographic cringe, and it always comes from treating the party as a sketch. The cure is the register rule — same formality, descending detail. The photos from weddings that followed it age beautifully.
Planning a real wedding? The house fits grooms and their parties across Europe on the proposed 2027 programme — bring the date and the venue photographs to the first fitting, and the calendar is planned backwards from the day.