Very do-able! My family did the same thing with 9-15-17. 15 and 17 were girls and the 9 year old was a boy. We were all about average for our ages and we fit comfortably without tripping over each other. We were hardly in the room except for bed, shower, and TV before bed. Other than that we were out and about. We never had any trouble with the size of the room compared to the amount of people in the room.