Starships possess a few minor amenities to make long trips bearable!
SHIP'S HEAD
First of all, are you out in deep space and you really need to "go"? Never fear! All starships have a ship's head! It's conveniently located in the storage room, simply because there is no good place to put such a thing.
Ship's heads also possess a first aid kit for use in emergencies. These are kept stocked automatically by alliance spaceports.
LIVING QUARTERS
Living quarters are the center of most amenities, logically! Living quarters are typically found on larger ships, and tend to be centrally attached to a "hub" room. This hub will possess a tiny, single shower that you can GO into. It has the usual START and STOP commands.
Also in the hub, you may CLAIM a living quarters if you have a key to the ship. This will lock a living quarters so that only you may enter it! If you wish to give up your room, you may UNCLAIM it later.
If you own the ship, you may OVERRIDE a living quarters lock from the hub in order to forcibly unclaim it.
Once inside the living quarters, you may ALLOW anyone you brought with you to also be able to get past the lock. If you change your mind, you can DISALLOW a person.