When it comes to weddings, it's probably best for the groom to be as simple as possible. A glen plaid may be a bit bold for her big day. That being said, you should look and feel good too. If the ceremony is an outdoor affair, a khaki suit is literally the coolest thing a guy can wear when dressing up in warm weather. This cotton three-piece by John Varvatos has slim peak lapels for a crisp, more formal look. And unlike her dress, you'll be able to wear it all summer long—either as a suit or sporting the elements seperately.