The Princess Diaries is a story of a girl who has lived an ordinary life as just that "plain and ugly" type. She isn't popular in school, and has lived without a father her whole life. When suddenly her rich grandmother shows up in her city and reveals to her that she's a princess, her father was a prince, and she was soon to be the next queen of some foreign place she's not heard about. I think this movie is funny and emotional at the same time as you watch "plain and ugly" girl turn into "beautiful, exciting, and popular" princess. She struggles as she goes through being revealed to the public, losing her friends to popularity, and just other dramatic scenes. I think this movie has a good ending, as Mia (Julie Andrews) chooses to be queen, gains trust back in her friends, and makes peace. The rating of this movie is G for general audiences. I believe, as do the makers of this film, that it is suitable for all audiences, and I'd recommend it for family movie nights.
I love watching this movie with my younger niece. We choose this one a lot for "girl nights in" when we pop popcorn, eat ice cream, drink cokes, and watch "chick flicks." It's great for that.