Get a watch with a plastic or titanium case to keep the weight down. Then experiment with different bands. If you’re not a fan of the traditional metal link types, look at bands in silicone, nylon, and leather. Find out the distance between the lugs on whatever watch you get (it will probably be included in the description) and look for bands in that size. Any band with the right lug width should fit your watch just fin.

I also recommend bands with quick-release pins. They make it quick and easy to switch bands and do not require any tools.