Get Yourself A...

Down Vest.

It'll be your greatest fall investment believe me. You can dress it up or dress it down. It is the perfect thing to throw on when it's too cold for just a sweater but you don't wanna throw on a jacket cause it's too restricting or too hot. Look for it in classic neutral colors such as navy and black so you can wear it into the office with your business attire. Also don't limit yourself to the North Face Model shown here. Plenty of other designers are making them for this fall. Just be sure to get one that fits right. It should be snug around the chest (not constricting) and hit you at the waist.