Thank you all, and especially
@Suzanne B. for finding the Starfish pendant (and also the Frog pendant - it's adorable!) I hesitated to buy the starfish at first because the picture on the listing was poor and I couldn't find a good picture of the pendant. But they are rare and I am glad that I decided to buy it.
It was difficult to find a good charm for the dark denim rogue. I usually try to match the hardware on the bag to the fob but not always, if the fob that I think looks best has a different color hardware then I pick the best charm IMO. But this bag has a lot going on and adding another color hardware made it look very busy. Plus, the thick hardware rings at the base of the handles don't work well with the attachment hardware on many fobs. The opening is too small to attach, or the fob sticks out at a funny angle when you attach it.
I tried most of my gold fobs and they didn't look quite right because of the different color gold hardware or sometimes the subject of the charm wasn't a good match - like some of my more decorative and fancy charms.
I have charms with hardware that are gold, light gold, antique gold, brass, rosegold and silver, and none of them worked well with the gold on this bag.
I didn't know the meaning of the "OL" hardware code on the style number so I "chatted with a specialist" on the Coach.com website and she told me that OL stands for "old gold" - who knew?
I was just about to use my gold leather Koi fish charm on a gold ball chain - and I think it looked okay, when I remembered my new starfish pendant. As soon as I tried it I thought that it was the best option. It doesn't exactly match but it goes well with both the bag and the hardware.
Anyway, I am very happy with my beautiful new bag at a great price and my lovely new starfish pendant!