Guys don't really have a myriad of accessories to obsess over. Most don't wear much--if any--jewelry, or carry a bag, or put things in their hair, or have much use for scarves. It's all the more reason that a man's choice of sunglasses carries a lot of weight.
The never-fail option is classic aviators, which were first developed by Ray-Ban way back in 1937. According to Wikipedia, aviators are defined by their "dark, often reflective lenses having an area two or three times the area of the eye socket, and metal frames with wire temples which hook behind the ears."
Of course, most of us simply know them when we see them. Here are some of our favorite, modern takes on the eternally cool aviator sunglasses.