Reddit mentions of Beauty: A Retelling of the Story of Beauty and the Beast

Have I got a list of recommendations for her.

Fantasy

Patricia C. Wrede's Dealing With Dragon's series was one of my all-time favorites when I was in middle school. It's a great story about an unlikely princess who offers herself as a captive to a dragon in order to escape the monotony of palace life, and ends up saving a kingdom.

Malinda Lo's Ash is a thoughtful retelling of Cinderella, with an unexpected twist.

Laini Taylor's Lip's Touch is one of those rare, beautiful books that managed to transport me to another world in a way I haven't experienced since I was a little girl reading Laura Ingalls Wilder. The book has three separate stories, each in a new setting and with new characters -- the only theme is the "magic" of a kiss, and I honestly can't praise her writing highly enough.

Dianna Wynne Jones' Howl's Moving Castle is one of my absolute favorites, although Jones has a plethora of wonderful works to choose from.

Robin McKinley also has an impressive library of works, though my favorite of hers is Beauty. It's a retelling of Beauty and the Beast that I've always enjoyed, particularly in how she depicts the secondary characters (Beauty's family and friends).

Kristin Britain combines the classic interests of young girls everywhere in her Green Rider series, which follows a headstrong young woman as she's accidentally inducted into the Green Riders, messengers of the King. Features horses, forbidden romance, duty, feminism, and magic. Also, I'm not good at selling awesome books.

Urban Fantasy

Cassandra's Clare's Mortal Instruments series is a well written YA urban fantasy that I've quite enjoyed reading. Basically, there's a class of angel-descendant warriors who fight the good fight against demonic forces . . . but it's not as black-at-white as it first appears.

Sarah Rees Brennan The Demon's Lexicon. I can't praise this series highly enough. First off, the I never saw the twist at the end of the first book coming, which is unusually awesome -- I read so often that (especially in fantasy) a lot of themes and plotlines can get pretty predictable. This one was a stunner. Second, with each book, she chooses a different protagonist as her main POV. So book 1 is from Nick's POV, book 2 is from Mae's, and book 3 is from Sin's. Since Nick, Mae, and Sin are present in all three books, it adds an interesting and unusual layer of depth to the books.

Neil Gaiman. No doubt you considered Gaiman already and discarded him. Don't. Gaiman has some really fantastic books that you don't necessarily need to have an appreciation of satire or subtle humor to read. He's a very talented author, and his works are varied enough that you could get her started with something like Stardust or The Graveyard Book and she'll gravitate on her own to his other works.

Dystopian Futuristic all are YA and have happy endings

Suzanne Collins' Hunger Games trilogy, starting with "The Hunger Games," and ending with "Mockingjay." I highly recommend these. Everyone I've lent them to adores them, even when they started out with a "Meh, fine, I'll read it because you're bugging me to," attitude. Basically, there's the capital city (Panem), which rules over 13 districts (although one of those districts has been wiped out). This society exists in the aftermath of some sort political upheaval, and we're given to understand it's North America in the far future. The districts are repressed, deprived of food, and harshly punished for any perceived treason. The capital lives in wealth and decadence. Once a year, to remind the remaining 12 districts of the cost of rebellion and why District 13 was eradicated, the Capital holds the Hunger Games -- two champions, one male and one female, are chosen by lottery from each district. The 24 champions are then taken to a specially designed arena, where they must fight to the death. The last remaining survivor wins food for their district for 1 year, and a lifetime of wealth for themselves. Katniss, the heroine, volunteers herself in place of her little sister (who's name is drawn), and sets off a chain of events she never anticipated.

Scott Westerfeld's Uglies series is another great dystopian futuristic sci-fi. It examines concepts of equality, gender, sexism, and personal worth. Highly recommend.

Steampunk/Historical fantasy

Naomi Novik's Temeraire series re-tells the Napoleonic Wars . . . if dragons existed. They're beautifully written, and it's fascinating how she weaves dragons into the socio-political history of the world, even to the extent that certain world powers have shifted in their influence due what types of dragons are native to them. A great series overall.

Gail Carriger's Soulless series is set in a sort of steampunk/ supernatural Victorian London. The writing style mimics Jane Austen, and her depiction of supernaturals is fascinating and interesting. It's a bit of a fluff read, but still worth it.

Historical Fiction

If your sister is into historical fiction, I highly recommend Ann Rinaldi, most especially A Break With Charity and Time Enough For Drums.

My own love of history was sparked by Esther Forbes' award-winning book Johnny Tremain and Elizabeth George Speare's Calico Captive. Johnny Tremain takes us to the beginning of the Revolutionary War, from the perspective of an injured silversmith apprentice-turned printing press apprentice. Calico Captive was based on the actual journals of a captive of the French-and-Indian war, and recounts the experiences of Miriam Willard, a young English colonist captured by Indians and sold into servitude for the French.

If she prefers speculative historical fiction, Stephen Lawhead's King Raven trilogy tells the story of Robin Hood, set during the time of William the Conqueror.

Other stuff

Finally, there's Justine Larbalestier. I've read two of her books -- How To Ditch Your Fairy and Liar. I recommend her based on Liar, but How To Ditch Your Fairy was . . . cute, I guess? I honestly don't remember it very well, just that I wasn't hugely impressed given the reviews that had convinced me to read it. The hype didn't live up to reality, for me. She's alright, though.

Also, have her sign up for goodreads.com. She can put in the books she likes and look for recommendations based on her interests, plus read reviews, etc.

ETA: In one of the comments, you mention that she has a short attention span and tends to skip over detail-oriented writing. In that case, I suggest getting some short-story anthologies, like Legends, Smoke and Mirrors, Kiss Me Deadly, and the aforementioned Lips Touch.