Warmth/Comfort:
* "The coat was as soft as a cloud, enveloping me in its warmth."
* "His coat felt like a warm hug on a chilly day."
* "The fur coat was as cozy as a downy blanket."
Protection/Style:
* "The raincoat was as impenetrable as a shield, keeping me dry in the storm."
* "Her leather jacket was as sleek and smooth as a panther."
* "His tweed coat was as timeless and classic as a well-worn book."
Other:
* "The coat was as heavy as a lead weight, dragging me down."
* "The old coat was as faded and worn as a forgotten photograph."
* "The coat was as colorful as a rainbow, catching everyone's eye."
Remember to choose a simile that fits the context and the type of coat you are describing.