I'm planning on renting out the basement going forward, she is going to be with us for what could be 6 months or even a year.
I think I'm going to "do it right" and slow-roll my way through improving my basement and making it livable and will have her in our guest room for now and if that doesn't work (privacy wise) my wife and I will move our bedroom down there and let her have the half story upstairs (then she gets her own bathroom).
I would rent her the upstairs now but my wife loves it up there, we have a huge walk-in closet (6 by 10?). But it's your normal .5 story, poorly insulated, barely vented, and has knee-walls. Even with central air we need to run a window unit in the summer up there or it gets 90 degrees.