Take some comfortable clothes with a loose waist because you'll be sitting a lot and waistbands get tight.
I used to take sweats instead of PJs because you could go anywhere in them without a robe.
Slippers and some comfortable shoes
Take plenty of whatever soda you like to drink because there is a lot of sitting around and talking and you'll be thirsty. And some little candies or snacks that won't dirty your hands. Wetwipes come in handy.
Something to read for when you're laying in a strange bed with your mind racing.