I once asked my friend, children's writer
Carol Ottolenghi what made a good young adult story. First of all, it must be a good
story. if you don't like the story, your kids probably won't either. Young adult is a libarary classification of stories for
teenagers. Teenagers have a
clue. Granted the number and quality of their clues may vary, but they are very well aware they are NOT children. And will remind you so whenever you remind them they are not
adults.
It's okay to find the books for very young children silly. After all, you aren't six anymore. But works for your teenagers can't be. Any story that insults your intelligence will probably insult theirs. Unless it's about cars, Daredevil or something else you personally find trivial.
Second, a young adult story should offer guideposts. Offer them tools for the world that is changing around them. Young adult stories do NOT avoid death, sex, or any other of the problems life presents. They will be dealing with these things soon enough, and if they are like me they'll be dealing with sexual urges even before that first pubic hair rears its ugly head.
The characters in a good young adult novel will illustrate strategies that can be used to overcome problems. As humans, we face a lot of problems. The biggest difference between adults and children is how we go about solving them.
A good example comes from my friend Ron Sarti's novel The Chronicles of Scar. It has all the makings of a good YA yarn, a decent adventure story with lots of swords and a bit of sorcery. his protagonist, Prince Arn, might not seem like a good role model. He steals, he lies now and then, he hires prostitutes. He kills. He faces abusive adults and overt cruelty.
But Arn is a complex character, who grew up a homeless orphan who takes a lot of baggage in life. But Arn as narrator is completely honest to the reader, honest to his friends and honest to himself. Though a Prince, he rarely throws his weight around, he listens to people, because he knows his title doesn't make him omniscient. He goes to war not for glory but because he realizes he has little choice.
Because Arn is honest to his readers about everything, and because his methods of dealing with problems are sound, he offers a solid role model for kids, without pose. His plain speech is clear to both adult and child. He makes mistakes, but he deals with them. He pays attention and learns from others who have shown competence. Jerry Falwell might hate the book, but I'd recommend it to any teenager, particularly boys who might find the character compelling.
The good young adult novel is not dumbed down. Kids got enough of that in grade school. Rather a good story offers a realistic picture of life spoken plainly. If a book does that, and it's a good read, you might want to leave it where your teenager can find it.
For outstanding youg adult stories you might want to look at Newbery Medal winners. You'll enjoy them too. And if you've both read the book, you'll have something to talk about.