If you do have bedside tables, there are some other items you may want to include, leaving enough room for a glass of water, glasses, and other things.
While an alarm clock is probably old-fashioned, some sort of clock is not a bad idea. But the times they have a-changed. Today's guest likely has their smartphone or tablet near them and uses it to tell time and to wake up to, and probably to read and listen to any music they want, as well.
Toward that end, have some kind of card made up that has the wi-fi network name and password, so they don't have to ask, and keep a Bluetooth-linked sound device nearby or set of headphones in the drawer. They may have some music they want to unwind with, or a certain podcast or guided meditation they like to listen to before bed. Having a Bluetooth-linked speakers or headphones to pair to makes them feel at home. As with the wi-fi, just having the name of the device and instructions printed up and on the table is a thoughtful move.
To really spruce things up and make guests feel welcome, place fresh flowers near the bed. Ever dream of being a B&B-keeper? Now's your chance. A basket or tray with towels, a fresh bar of soap, any other bathroom essentials you can think of, crisply waiting for them in the guest room will not only make them feel so cared for, it will add a charming touch to the room.