You really can’t go wrong with a long black coat. It is one of those standard pieces of clothing that should probably be in every woman’s closet. The reason they are so versatile is that black is a neutral color that can go with just about anything, and the fact that the coat is long helps you avoid sticking-out issues from what you wear underneath, by covering up your entire outfit, no matter what the color.
Three examples that I think look great:
Womens long black coats pictured:
Left: BGSD Women’s Long Wool Blend Walking Coat in Black, Chocolate, or Camel
Middle: Merrell Women’s Jacqueline Insulated Long Car Coat
Right: Allegra K Long Sleeve Notched Lapel Belted Trench Coat for Lady