@Quincy
Not much, to be honest!
All bedside tables have a lamp and coasters. I also put a carafe of water and drinking glasses in each bedroom. In two of the rooms, this is on the bedside table, but one room has a rather small bedside table, so those items go on another surface.
There are other places in the room where guests will find reading materials, e.g. bookshelves, magazines (travel magazines or magazines in the guest's language if I have them) and leaflets and maps.
I think it's better not to clutter up the bedside table as guests will have items that they want to place on their, e.g. their phone or a book that they brought with them, earplugs, earphones, reading glasses, jewellery they take off at night, whatever. It's important to leave them space for these items.