My DD29 is calling for "cocktail attire" for her August wedding. It's 4pm, on a mountain top in western Massachusetts. My youngest, DS19, is a bridesman, and he'll be wearing a velvet jacket with chinos. It was chosen because the color matches the bridesmaids, and was on clearance--he didn't want to dress like a groomsman, but he wanted to fit in. He can take the jacket off, pretty much as soon as the photos are done and he enters the reception venue (which is inside--wedding is outside). We'll see how it goes. The rest of the guys in the bridal party will be in suits--but again, who knows for how long after their grand entrance.