Congrats Chenchuan,
That's a lot of empty nest all at once - I wish you a smooth transition.
As for which school, since she has an older sister in Boston, she has a pretty good idea of the distance thing. As you say, she can't go wrong. Princeton certainly has better weather than MIT. My guess is that she will get a vibe from being on campus and that will be that.
Best Wishes,
Grinity

Coaching available, at SchoolSuccessSolutions.com