I decided that dying the towels would require learning a new skill that I have no interest... with no guarantee that I would end up with the color that I wanted.
Tartan suggested putting some trim on the towels and that gave me the idea of cutting off the existing borders and replace them with a border using some fabric from my stash. I have no idea how this will hold up, but I have more of the same towels that haven't been changed so... win... win...
Thanks for brainstorming with me!