What if the hotel does something to the guests?
Because there's no way all the characters are going to be evil from the get-go like Ryan has said, it just wouldn't resonate well with having no one to root for given that they are all evil? All the workers there would have evil plans but the new guests would slowly be taken over by these forces?
Like for example, remember how Murder House was messing with Ben and made him sleepwalk and almost put his hand on the stove? What if that's something along the lines of what happens in Hotel? The longer you stay the more it consumes you? Iris could offer special deals on rooms to extend their stay or have some outside force that chooses certain guests and traps them so they are slowly converted to being evil? That way the new guests could be evil and murder people but we would still be rooting for them to somehow be saved? Or there's always the possibility that if they did in fact escape the hotel, that darkness that consumed them stays with them, thus influencing events that could relate to future seasons?
