For a nice watch, if I want to go the extra mile, I wrap it in bubble wrap and put it inside an insulated souvenir cup with a lid. Then I put that in a shipping box with additional bubble wrap or other packing material. The cup costs a few dollars at the supermarket or discount store, but I look at it as a small extra gift for the person who purchased the watch, and the watch is extremely safe. You could step on the package without damaging the watch, and it is also safe against water since it is sealed inside the lidded cup.
I have also used the small reusable food storage containers, or other small plastic boxes.