I love seeing guys in a colorful or printed tie or bow tie to put some personality into their suit or tuxedo. You can find a wide range of color and fabric options for ties, bow ties, vents and cummerbunds at the men’s store or rental shop, but you may also want to shop at specialty stores or craft your own.
TieCrafters.com can custom make any of these items in a fabric of your choosing. You’ll see a lot of their work in Martha Stewart Weddings magazine.
Other accessories to dress up his look include: Colorful or patterned socks (you've seen the shoe/sock shot in a lot of real weddings), great shoes and cufflinks. All of these items can be worn after the wedding and the cufflinks can be a great gift you or parents can gift the groom.
I’d skip a suit in a wild color -- remember the powdered blue ones from the ‘70s -- because you want your pictures to look timeless.