If you want to look cool and fashionable, you could choose the white frames of sunglasses, especially with the round lenses. This type of sunglasses is so fashionable and hot this year. If you just want to show the gentle style, you could choose the black lenses sunglasses with good materials.
If you want to be cool with sunglasses when you wear a suit, a pair of black sunglasses a good choice. You can choose a pair of round black sunglasses, rectangular black sunglasses and square black sunglasses according to your face shape. Besides, Ray ban aviator sunglasses is also a good choices to make you handsome and cool when you wear a suit. In a word, you shall try to choose some simple designed in style and colors of the sunglasses if you want to look cool with the suit.
As a matter of fact, I rarely see people in suit wear sunglasses. Since sunglasses are especially designed for outdoor activities, not for parties and lectures. Maybe you should just wear proscription glasses with nice frames to enhance your looks. But if you insist, I recommend aviator sunglasses for you and the actor in Matrix also wear sunglasses in suit. Hope you have a try on them.