Eliminate Frozen. As much as new material is more intriguing to you and your wife, this show is a pass. Similar enough to the movie and the differences didn't make me think I'd be disappointed if I hadn't caught the show. Not trying to hate on Frozen or anything because I think it's overall a good show (and I loved the movie), just trying to be honest.
That leaves Carousel. I've seen it twice and it definitely improved by the second viewing. It's not as lavish as Frozen and slightly outdated, but the score, voices and the choreography are fantastic and reasons enough to check it out.
Final thoughts, if you want a grand Broadway experience, go with Frozen but I feel you have shows that fill this need already on your list. If you want a classical theater experience that has more serious themes go with Carousel. At the end of the day, it's up to you :)