I agree with you, I feel that Coven and Asylum have quite a few parts that could be awesome in a maze.
I have yet to see Roanoke so I cant give my full opinion but from what I've heard it definitely could be its own house. I would be okay for them all to be in one house but I could see them do two seasons this year and two seasons next year since the new season is said to come out Fall 2017. I am a huge fan of the series and would love to see it at Horror Nights for awhile. Just a thought.