I recently had a platonic female friend stay over at my apartment, and when I told my parents, they gave me a hard time for making her sleep on the couch and not giving up my bed.
Look, if you're my friend, you get the couch. I don't care if you're a girl, if you're just a friend, you get treated like all my other friends. If I'm trying to fuck you, you get the bed . . . with me in it. That's a very simple, and I think logical, rubric.