Hooray for May. It's one of the loveliest months of the year, and I'm glad searching for and discovering new books has added to your joy.
I view books as "clean" based more on the intentions of the writer, and mine as a reader. The worth of the book as a whole is far more significant to me than the word choices or whether there are more mature themes.
If a book is littered with profanity it can become eyesores on the page, but if it's sprinkled in as a realistic part of a character's vernacular then I accept it as such. Really, words have the power we decide to give to them. Classic literature of the past contained words and phrases that were considered to be profane, vulgar, or salty then at the time they were written. There's also plenty of ugliness from words that are not profane, and goodness from words classified as such. Context is what matters the most to me. One of my favorite leisure books last year was "The Goldfinch" by Janet Fitch, and the teenage protagonist's roughhewn, abused but resilient friend has quite a mouth, but it's fitting to his character. It would be a shame to miss out on the book due to something that was tangential to the story itself. As for sex, since it's a natural part of human life, it's written about or referenced in many books. I can understand avoiding erotic fiction, but sexual content in a book that doesn't revolve around sex isn't the same at all. Some of the books that have expanded my compassion and been to significant to me like "I Know Why the Caged Bird Sings" and "The Color Purple" have been banned due to sexual content, and that's a shame to me. Some celebrated classics like "The Canterbury Tales" are proliferated with sexual innuendos.
Anyhooo. I'll try to comply with the request.
I think you might enjoy Willa Cather's books. In particular "The Song of the Lark" because it is about a vibrant songstress named Thea who uses music as a companion in her loneliness, as artistry, and a way of fulfillment. She also has some insightful observations about Christians. The end of the book isn't as good as the beginning, but it's all worth reading. "O, Pioneers" and "My Antonia" are also very good. Jane Austen and the Bronte sisters wrote books that are engaging but not really that provocative. "Emma" is a fun read.
Tracy Chevalier's books tend to be PG but with more mature themes, like "Falling Angels" and "The Virgin Blue." I know you've already read "My Sister's Keeper" by Jodi Piccoult. Her books are very formulaic, but I've still liked some of them. The impetus for the plot of "The Tenth Circle" is an alleged date rape, but the heart of the story is really the relationship between a teenage girl and her father. It's what is of far more importance than the few pages relating to sex. If you can get beyond the sexual content I think it's a book that would be very meaningful to you. Another book that in particular I think would have some relatable aspects is "The Poisonwood Bible" by Barbara Kingsolver. "Some Luck" by Jane Smiley is about a farm family, and is very good.
E. Lockhart, also credited as Emily Lockhart, has written children's books as well as "young adult" and "adult" (not in
that way), and my favorite is "We Were Liars." It's a YA book, but it topped several lists of the best books of 2014 for adult readers, too. The protagonist is our age. Other favorites from last year are "The Girl Who Saved the King of Sweden" by Jonas Jonasson, "I'll Give You The Sun" by Jandy Nelson (a YA writer).
This is a list of teen books that might be of interest:
Best Young Adult Novels, Best Teen Fiction, Top 100 Teen Novels : NPR
I definitely recommend "The Giver" series.
Taste Kid lets you enter the name of a book, author, song, movie, or TV, and then it will generate recommendations for things you might also like. It doesn't really have that expansive of a list of books, but it's worth trying.
TasteKid | Recommends music, movies, TV shows, books, games
ETA
I wanted to add: Veronica Roth (Divergent), Sue Monk Kidd (The Secret Life of Bees), Kate Chopin, Mitch Albom (Tuesdays with Morie), Frank McCourt (Angela's Ashes), Markus Zusak (The Book Thief), Rebecca Skloot (The Immortal Life of Henrietta Lacks) and Laura Hillenbrand (Seabiscuit).
John Green is such a huge part of my childhood. He's old enough to have perspective and young enough to still be in touch with adolescence, and I love his writing style. He does write a bit about sex sometimes, but not gratuitously. There is some language. Still, his books are written for YA readers.
Have you read "The Help" yet? I liked the book better than the movie.