Natural leather is fun because it's visibly absorbs your history really quickly. The darker leather definitely gains character as well, but it's not quite as apparent. I have some older stuff that's been dyed, and it shows wear:
This is my main color palette, though I also have another really dark chocolate brown that isn't shown here:
As far as the bracelet width, the limiting factor is the closure hardware. I do about 15mm wide so that there's enough meat left on the leather after I punch the hole for the stud. If you want something narrower, I can always just taper the middle, but the ends will have to be wider where the stud attaches.