If you're looking for manga similar to Ashita no Familia, you might like these titles. All recommendations are made by Anime-Planet users like you!
In both series a human boy lives in this big mansion with a number of monster girls for some reason. Oh, did I mention there are the monster girls in both series?
Anyway, Kaibutsu Oujo has cooler characters and (probably) better action scenes, but Ashita no Familia doesn't come all that far behind when it comes to being entertaining.