What most naturally follows?

How to have a birthday sleepover at a hotel
Ask your parents!
It's up to your parents if throwing a hotel slumber party is in their budget. It's a good idea to have your parents sleep in the room next to you and your friends. Getting an adjoining room would be a good choice.
Pick a theme! There are so many themes to choose from. Themes can be pretty much anything; from tv shows to winter.