Reach for a navy long sleeve t-shirt and navy jeans to assemble an extra stylish and modern-looking casual ensemble. Add a pair of dark brown leather casual boots to your outfit to instantly turn up the classy factor of this look. This one is a wonderful choice if you're piecing together a well-coordinated ensemble for summer-to-fall weather. As you see here, as a 30-something Millennial guy, you have a wide range of outfit options.