I think it's important not to stare on the money too much. A honeymoon is a honeymoon and if you have already invested a small fortune into a wedding then you might as well choose a hoonmoon destination that will be equally as fullfilling.
Like the above poster said, the ports should be a major decision factor as they can make or break your cruise as much as the quality of the ship. It's without question that the Celebrity Silhouette docks at much more romantic places which are in my opinion more fit for a honeymoon. So I suggest writing down all destinations and jotting down whether they have anything interesting to offer. There's nothing better than killing two birds with one stone. If you are able to combine your honeymoon with places and experiences you have been itching for then you can save money on not having to visit those places at a later stage in life.