If I have extra peel and stick tiles, what should I do with them?

you could try a small area to see how it goes.

I did and I love it. I used a horizontal stripe (beach wood) and it looks great! I have used it in the bathroom also.

Line the bottom of a tray.

How about use some to cover square containers of various sizes to use as a catch-all or to hold specific things in the same room as where the tiles were used in your design. It will give it a pulled together look. Other idea - to cover some old worn out cutting boards to use as a "trivet" for plants, pitcher of lemonade...just nothing hot. Hope this helps.

You could use them to line a mirror

Thanks guys

You can line a cuboard drawer.