Most people don't realize you can request items from your cabin steward:
Pillow options: most cruise lines have different pillows. If you don't like the pillows you have ask what else is available. Some cruise lines have a pillow menu!
Bed Configuations: When your agent books your cabin, they request what you want. However, I've found out many times the cabin stewards don't read the reservation. Ask them to change to either together or apart if they are not what you want
Power Strips: You cannot take a power strip on a ship with a serge protector on any ship. Most have these availalble for your use. If there are not enough electrical outlets in your cabin, ask for a power strip. The newer ships have many electrical outlets, but some of the older ships don't have enough. Check the USB outlets, some don't work! You won't find out until you wake up and your phone has no charge!
Bath Robe and Slippers: If you have a suite, they are automatic. If you are in a regular cabin and you want these, just ask.
Wine Glasses: If you brought on your own bottle of wine to be consumed in the room, ask for wine glasses.
Hangers: There are never enough for us, and we always ask for more, It's never been a problem.
Kettle: If you like to have tea or instant coffee in your room, most cruise ships have them on board. If the cruise ship has ever sailed in the UK, they will have them and you just have to ask.