Adding a cool frame is a great way to make mirrors more decorative. Here is one idea https://www.hometalk.com/30275790/sunflower-sunburst-mirror-made-with-cardstock or for a square or rectangular mirror, you can add a tile edge!
Do you want to hide the mirror or spruce it up? A lightweight frame, glass frosting spray and adhesive films are some options.
Check out the new adhesive films and window films. You can disguise the mirrors or use a dark mirror film to work with what you have. I've seen everything from wood to stone to other decorative films. I've seen a few at stores, but, more online at Wayfair and Amazon.
You can buy vinyl tile sticker to decorate your glass doors. https://amzn.to/2VFGH4P