This is a really hard one, how about the new Jon Stewart book?
The Daily Show with Jon Stewart Presents Earth (The Book): A Visitor's Guide to the Human Race,
I have read the Vampire Academy series, really enjoyed it, and they have a set for the first four books, by Richelle Mead,sometimes younger people don't realize they would like a genre that their school may not be introducing them too, like fantasy, then after they realize it is out there, it opens them up to reading, that happened with my son.
The Shopaholic series by Sophie Kinsella, I think they would be okay for a teen, and the first few are very funny.
Hope this helps some, I will keep thinking! What a challenge...

This might be heresy, but since I run the site I'll go out on a limb and say it... do you have to get her a book? Maybe this is one of those times where a gift card is the right answer. It could always be a gift card/certificate to a book store so she can at least try to get a book... but could use it on a blank journal or cd or some such. :-/

Peter
(The guy who runs Flashlight Worthy)

She does sound like a little princess. I would recommend "Princess Diaries," by Meg Cabot http://www.megcabot.com/princessdiaries/pd_v1_princessdiaries.php

And, she sounds like a 'girly girl' so I recommend: "Legally Blonde," by Amanda Brown. http://www.amazon.com/Legally-Blonde-Amanda-Brown/dp/0452283736

But, it seems like teenagers today are into the "Twighlight" series. I never could get into reading about demons so my boys didn't either. We were into the Harry Potter books and "Sports Illustrated for Kids" type of family. Teenagers today seem to get into twighlight though: http://www.stepheniemeyer.com/twilightseries.html

Cook books is a great idea. I was wondering what to get for my son who loves to cook. Thanks,
M

Oh, one other idea -- the Hunger Games Trilogy in a box set:

http://www.amazon.com/dp/0545265355?tag=fw-hp-20

I devoured them and I'm a 40 year old male. Since the protagonist is a teenage girl, she'll like them even more than I did.

Marilyn, I love the books I got for my two older nephews - they share a house, love to cook, and really LOVE to grill, so I got one of them Stephen Raichlen's Barbecue book, and the other is getting Raichlen's Grill book.

He just got one of those fancy dancy chrome grills; the barbecue book is perfect. That saved time!! Thanks again!!

Peter: I've never heard of that trilogy; I'll have to google.

I definitely say the Hunger Games too! Every kid I've met who read them loved them (and every adult lol) They aren't so 'teen' that she might be offended by you giving her them (like twilight, if she hates that sort of thing) and they're definitely interesting enough to catch her attention right away.

Chicken Soup for the Teenage Soul.

Dash and Lily's Book of Dares by Lily Cohn and David Levithan. I stayed up way too late last night because I could NOT put it down. It is about two quirky 16-year-olds, so it could quite possibly show her a different side of others her age. It's smartly written and appropriate for a 16-year-old. It's by the same pair of writers who wrote Nick and Norah's Infinite Playlist, which is quite possibly a movie she has seen.

The Immortal Instruments series by Cassandra Clare is also a nice series for YA. It's main protagonist is a fairly strong teenage girl, though it doesn't seem that way at first. The main thing that appealed to me about the series was the way that the writer incorporated so many different fantasy/paranormal elements into her world. There's a little bit of everything in it from vampires to angels to humans to demons to witches and everything in between.

A series wrote in very much plain teenage English is the House of Night series by PC Cast and her daughter. It is a vampire series, but in this one, vampirism is a recessive gene that appears in teenagers that is very much public knowledge. If it comes out, they get sent to their local House of Night to learn the things they need to know about their new world.

If she's not so much into reading, but you want to try and turn her on to it, the second one would probably be the better of the two simply because as I said, it's written very much in teenage English. The dialogue sounds like things my teenage sisters would say (and I've heard them say on some things). Though, to be honest, the Immortal Instruments series is a better story.

The Hunger Games trilogy, without a doubt, will captivate her if she just gives the first chapter of the first book a try!

I personally recommend:
Meg Cabot's The Mediator series (these are short enough to be read in a day)
Maureen Johnson's Suite Scarlett, 13 Little Blue Envelopes, and The Bermudez Triangle
John Green's An Abundance of Katherines, Looking For Alaska, and Paper Towns
Cynthia Leitich Smith's Tantalize
Lili St. Crow's Strange Angels

I'm 21 and I've devoured every book John Green, Maureen Johnson, and Cynthia Leitich Smith have put out (I started reading them back in high school). Libba Bray is another good YA author, but her Gemma Doyle books are HUGE and if she's not a big reader, she might not be able to get into them. You might want to check out some author's online followings to get a feel for what other people her age think of their books, too.

But I have to agree with Peter. I know it's impersonal, but maybe you should just get her a giftcard and let her find something on her own? You can always strike up a conversation with her about what she ends up getting so you can have a general idea of what she likes for next time. If she doesn't get a book, you can always ask her why not and find out what else she's into.

Neil Gaiman's "Stardust" would be my top suggestion. It has humor, it has romance, it has magic and suspense: and you can double-gift it with the DVD of the film version, too!

I absolutely adore Neil Gaiman and Stardust is a good suggestion - there is a beautiful illustrated hard copy edition which she would treasure I'm sure. http://amzn.to/hvvG9C 'Neverwhere' by Neil Gaiman is also a really involving read which I'd recommend for her http://amzn.to/dRg3Mn

When I was that age (and at a private girls' school - so maybe not that different from your niece?) - I read 'Forever' by Judy Blume...do you know if she's read the earlier Judy Blume books? It's the ultimate 'first relationship'/'coming of age' book for girls and would be my recommendation - cool aunt award would then go to you! :) http://amzn.to/g7lmG6

Good luck!

Prep by Curtis Sittenfeld. Great book!

Here's another suggestion: Pamela Frankau's "A Wreath for the Enemy", a marvelous coming-of-age story with just enough sophistication to pique the interest of any hip and worldly young woman. I remember just devouring it!

Melissa-
Sarah Dessen is a good author, I love "This Lullaby" and "That Summer"
Twilight is a good series too. I'm 19, I've read most of the popular YA books, including Gossip Girl and the It Girl series. The Private and Privilege series are also good. I also liked Ellen Emerson White's rewrite of The President's Daughter and that whole series. It probably won't help you now though.

kurt vonnegut safe and just weird enough to be enticing

noughts and crosses trilogy- by malorie blackman
this was an amazing book! i couldn't put it down, it is about racism, but the tables are turned. the government is run by blacks( or crosses) and the outsiders are whites who are poor and live in slums. this story is like a web, one huge friendship is changing everything- i would strongly recommend this book to anybody, no matter what genre you prefer, from romance to culture.