There are a few great places to watch the sunset. For the fun and carnival type atmosphere watching it from Mallory Square is very nice. It can be quite crowded there though. The sunset is BEAUTIFUL from the ship also. I understand that there is a way to get over to the little island just off of the port area that offers spectacular views of the sunset also.
You can't go wrong watching the sunset in Key West. You can almost hear is sizzle as it sets into the water!
Sue Ellen