Most men do not have much idea about the essential mens dress pants needed for their daily business wear or even something other than khaki pants during casual occasions.
Dress pants can bring about comfort together with style, but many men are confused between comfort and carelessly casual without style.
The basis of essential dress pants boils down to the fabric used. Let us review these few:
Worsted Wool
You can refer to mens suits fabrics for details on worsted wool, its grades and the various high quality worsted wool available.
An important fabric in mens fine clothing especially tailored ones; worsted wool should be the most considered an essential mens dress pants fabric to have in the wardrobe.
The fine texture of worsted wool without the fuzz (i.e. no itchy feeling) makes it a comfortable and lightweight fabric suitable for the year round during all seasons. Furthermore, the fine fiber allows a good drape for the dress pants without creating too much wrinkles.
Gabardine
A twill woven tightly of either wool or cotton. It is characterized by its diagonal twill lines at 45 or 63 degrees. It is an extremely durable fabric with hardly creases. The fabric itself usually comes in solid colors and can resemble khaki due to its color and twill weave.
Relatively to worsted wool, it has a silky touch with a firmer finish giving a good drape as well. The fabric’s weight can depend on individual designer though. In order to deviate from a khaki look, I would recommend going for a navy or charcoal or gray gabardine as an essential mens dress pants. These colors suits very well with most blazers or sports jackets.
Flannel
A medium-weight fabric that can be plain or twill weaved with a nappy finish to conceal the weave. It can also be produced by worsted or woolen yarn. It is very suitable for the winter due to it being heavier compared to other wool fabrics. It is a very lasting, rich, and down-to-earth fabric with a soft hand feel.
1940s was the time when dark gray or charcoal flannel pants showed its prominence as the trouser of choice. It basically matched with any other blazer or sports coat available. During current era, it still has its position as the essential mens dress pants. It allows an easy match with dark colored sweaters or even medium blue dress shirts. However, we would go for a wider color range as well as designs for flannel dress pants as seen in this light gray flannel pants from 
Brooks Brothers.
Calvary Twill
Twill is more of the way either cotton or wool has been weaved which is usually in a 63 degree diagonal direction with raised rib. Of particular, the calvary twill has been the popular fabric for essential mens dress pants due to its rugged but stylish feel.
Calvary Twill is a durable fabric with a stretch quality. It was originally worn for horse riding. With its sturdier weave, Calvary Twill has a casual feel suitable to be worn with blazers and dress shirts fitting into our current era of business casual wear.
Tweeds
This is a heavy fabric suitable for the colder months of autumn and winter. It has a rough surface that can be either plain or twill weave.
For dress pants, we would rather consider Shetland which has a lighter weight weave typically in plaids or stripes, and Donegal known for its specks of color nubs such as blue, red, and yellow throughout the fabric.
Linen
This is the summer fabric of choice for essential mens dress pants. It is known for being a fabric with strong and lustrous yarn. It allows an airy feel because it is being woven from natural fiber.
Linen is versatile in that it can be worn casually but still give an elegant and relaxed feel. For example, wearing linen dress pants with sandals or moccasins, tucked out dress shirts with or without a destructed jacket.
The fit for linen pants is generally different from usual dress pants. It should be worn loose and free to give a non-chalant styling that linen projects best.
Further References on Dress Pants:
Details on Dress Pants
Proper Fit for Dress Pants
