* Her smile was as kind as the sun breaking through the clouds. (This simile compares the kindness of her smile to the warmth and brightness of the sun)
* He treated her with a kindness as gentle as a summer breeze. (This simile compares his kindness to the soft and gentle nature of a summer breeze)
* His words were as kind as a warm blanket on a cold night. (This simile compares the comforting nature of his words to the warmth and security of a blanket)
Let me know if you'd like to explore other options!