From what I understand a Cruise Line Wedding be it on the ship or Castaway is pretty cut and dry. You don't get to choose alot of things doing it this way. Yes I have seen Brides post who have added color to their cakes, you get to pick from a few different styles for your floral, you can get floral delivered from an outside vendor. You CAN do a Sand Ceremony but the Captain will not do it you do it on your own.
My DD is doing her wedding on the Ship in November 2009. Here are some of the things we are either doing for sure or are in the works as far as I know.
1. I am going to order her flowers from an outside vendor, she wanted Hydrengas and they were not offered on the ship.
2. She has found a Photographer who is willing to do her Pictures, DD is paying for a stateroom for the photographer and a guest.
3. She asked if she could have color added to her cake (thanks DisneyDMBNut got the idea from you)
4. She is getting married on Deck 7 and her Fiancees mom will have just finished up Chemo so she asked that they be able to move the cake somewhere inside, and Cathy said she would place that request but it CANNOT be in Palo because of dinners and so on going on there and DD is fine with that.
5. They are thinking of the private room at Palo for dinner the evening of the Wedding (still in the works because they are not sure of how many people will be attending)
6. She asked if there was a way we could bring something else to use instead of the white bows that decorate the deck....Cathy was suppose to email the dimensions of the railings because everything must be able to velcro on. Also still in the works (thinking of what we could do that would hold up against the wind and so on)
7. She is making Welcome Bags for the guests just not sure if she will be shipping a box ahead of time or trying to pack or carry on the items to go into them.
I think that is about it for now that I am sure of. She catches me up when we catch eachother on the phone since she is in Dallas and I am here in Pennsylvania.
I dunno I guess if you want more control or more frills maybe a Wishes Wedding at Walt Disney World is the way for you to go. I guess that I was under the impression that a Cruise Wedding was suppose to be easier, less comotion, and a bit more laid back....am I so wrong??
I haven't seen any kind of enhancements or options available for the beach ceremony. I'm trying to figure out what the table will look like that holds the Sand Ceremony! 
but a while ago cathy sent me three pictures of what the current beach set up looked like. One of them had a bunch of tiki torch things and she mentioned that they were enhancements and that we could talk about all of the options. 
