One of the best fall/winter investments you can make is a pair of grey wool flannel trousers. The subtle flecked texture adds a little visual interest, and you can wear them with just about everything—from dress shoes and a blazer to suede boots and a heavy turtleneck sweater. A versatile, classic piece of menswear that will keep you warm and comfortable. Shown: Howard Yount [$190]. L.L.Bean Signature [$125]. Epaulet [$235].