Traditionally, casual weddings involve button-down shirts and nice pants, semi-formal weddings call for suits or tuxedos, and formal weddings involve to-the-nines tuxes or morning suits.
While the coat and pants of most wedding outfits are fairly basic, accent pieces such as ties, pocket squares, and vests can give the look a little punch. If your wedding color palette has an accent color, this is an excellent place to incorporate it. For instance, if the main wedding palette is lavender and dark green, consider accenting male attire with gold or dark purple vests and ties.
Vest vs. Cummerbund:
Cummerbunds are a good way to incorporate a strong, bold, single color into male outfits, while vests have the more subtle option of patterns. Generally, cummerbunds are worn with bow-ties, while vests can be paired with bow-ties or long ties.
Bow ties tend to make the neck area look thicker, which may be a concern for some men. Bow ties also tend to be a little more formal, making straight ties a great option for a semi-formal wedding. If using bow-ties, consider getting clip-on versions to avoid wedding morning tie-related panic.
Shoes and Socks:
Black shoes are typically worn with navy, grey, or black suits. Brown shoes may be paired with brown, taupe, or lighter blue suits. To avoid all sock-related crises, just mandate that socks match the color of the shoes or pants. Bring a couple of extra pairs of dark socks in case someone shows up wearing white.
Generally, suit or tux rentals are done at least a month in advance; rentals less than two weeks may incur rush charges. Since most groomsmen are fairly easy going about what they wear, style decisions can simply be made by the bride and groom, who can put in a single order for the whole wedding party.
Since many rental houses will charge extra if suits are not returned within 24 hours of the event date, be sure to put a trustworthy groomsman/best man in charge of collecting and returning all the suits. Farming out this task allows the groom to spend his first day as a married man sleeping in with his wife, rather than frantically counting cufflinks.