OK - here are a few I always take: ear plugs, eye blinds and personal reading light. Especially in a smaller cabin you if you are awake at night, or your partner is, you don't have another room to go to to read or watch TV. With the above it is easy for one person to sleep while the other is reading or watching TV.
Here is another I have seen mentioned (though I can't imagine why): air freshener.
As for bathroom items, I keep a travel bag packed all the time that I can just grab and go. It has travel sizes of everything and duplicates of things I would use at home. That way I don't have to worry about taking an inventory every time I pack.
But speaking of inventory, these packing lists have proven to us to be very helpful: