So I like NATO straps. My only problem with them is that the holes stretch and they stop fitting perfectly. Sure they're cheap to replace, but I would be just as happy spending $20 on something else, like a different color strap :D
So to prolong the life of the strap, I came up with a little something:
Scrap of thin leather
E-6000 (preferably with the narrow nozzle)
Put the strap on, see what hole you're going to use, and then cut a narrow strip of leather that will cover that hole and the holes next to it (just in case). Use the strap as a template and use a ballpoint pen to mark where your holes are going to be in the leather, then use whatever punch you want to make the holes. Glue the piece to the inside of the strap, using a pin or something to check hole alignment.
Ideally, your leather piece will be as wide as possible for maximum adhesion surface. You could probably back it up with some stitching, too. But E-6000 is pretty strong stuff.
Maybe the leather isn't all that water-resistant, but if you don't really get your watches wet, and just like the look of the nylon straps, this will keep them fitting snug for a long time.
Maybe a thin piece of silicon rubber from a pot holder or something for a waterproof version?