Well, the main characters would include Dracula who is in charge of the hotel and its rules. Vlad, for whom the stories are meant. Then there are the monster families. The werewolf pack, with their pack mentality and family values, would be important characters. And the mummy, with his ancient wisdom and unique abilities, would also be among the main characters in these bedtime stories.
Obviously, Vlad is central as these are his bedtime stories. Dracula, his father - figure, plays a major part in guiding him and in the overall hotel management. The Invisible Man could be another main character, perhaps getting into all sorts of invisible - related mischief. And the Witch might also be there, with her magic causing various situations in the stories.
Dracula is surely one of the main characters. He's the owner of the hotel and has a big role in the stories. Vlad is also a key character as the stories are his bedtime stories. And then there are likely to be other monster characters like the Frankenstein monster, the werewolves, and the mummies.