Your waiting room (WR) is a place where you can shift to before shifting to your DR, or you can even come here to take a break from your CR or change your script. It's just like a normal house with a bedroom, kitchen, bathroom etc.
What you want your WR to be is completely up to you, for example it could be a little cottage or a hut on a beach. Just make sure to script what you want it to be, optionally you could also script that you're safe (for those with anxiety), or to script you have pets there!
I've listed below some ideas for anyone who is struggling to think of something :)
(All pictures are from Pinterest)