I think "family friendly" is a fine alternate for "G rated," i just wasn't sure that's what you meant -- especially since you put it in quotes. But I would add that a huge percentage of all Broadway musicals, and and an even more huge percentage of them written in the 20th century, could be classified as either "G rated" or "family friendly," so I don't agree with your objection to THE MUSIC MAN in that regard.
Also, you didn't use this word, but I really bristle when I hear people describe THE MUSIC MAN as "corny" or "hokey." Yes, it's true that the Iowa character for the most part are simple people who tend to behave in hokey or corny ways, but that's VERY different from saying that the point of view of the show on the whole is "corny." In fact, I think it has a very smart and compelling premise.