Silly to give general advice like this. My wife loved it when I did a big trip with all surprise destinations. I just gave the weather forecasts.
I think I'll just tell her that morning that we are going away for shabbos. Her sister will take the kids, and she generally doesn't mind stuff like this. Not that I've ever done it before.
I promise I'm not copying AJK.
I just saw some space and decided YOLO.