Alaska or bust ...That company you booked your alaska cruise with matches on the smoking issue and same sex issue and also tries to match approximate age levels. The Balcony issue is very important to me on an Alaska cruise. For some reason I am assuming you are a woman. See you could get matched with someone who is a real "party animal" and then virtually have the cabin to yourself except the for the wee hours of the morning until the late morning or sometimes these type people dont come back to the cabin at all for several days except to get things they need.
That particular company will set up a message board for that cruise about 30 to 60 days before the cruise and that way you can post about yourself and what your "wished for parameters for a roomie" are and you are fairly likely to get some responses and then you can have the "ground rules" established before the cruise and that company would way more want two happy people roomies because then it makes their job easier.