I really liked the Uglies series but, I know I keep repeating myself, I really REALLY liked the Gemma Doyle series (The Great and Terrible Beauty). I can't remember if you've already read them or not.
http://www.goodreads.com/book/show/3682.A_Great_and_Terrible_Beauty
This series really grabbed me and scared me and I have been looking, without success, to find something that gives me the chills in this way. Not too scary.. just scary enough. Like a good ghost story. -
ACTUALLY: although I attached the link to the book review/summary I would not read it. It gives away too much of the story. When I read it I had no idea what was going to happen and I totally believe it was more fun that way. Trust me... see what you think. If not on vacation, at least sometime.
However, I would definely put this book
http://www.goodreads.com/book/show/112750.Darkfever Dark Fever (there are 3 out and one on the way) at the top of your list of book(s) to take on vacation with you. I bet you you will not be disappointed.
Did you read the teen vamp series, House of Night? It can be grating to some due to the language (very teen "it" stuff) I dunno.. I thought it was pretty hilarious (until the 5th book when I was sick of it).
http://www.houseofnightseries.com/
I see you have "Dead Witch Walking" on your to-reads ...
http://www.goodreads.com/book/show/30264.Dead_Witch_Walking I liked that book alot. I haven't continued with the series as it's a mass market paperback and I hate those AND because I own the others in the series and so my library books (wtih their pesky due dates) are at the top of my list.
There has also been alot of talk about the Maximum Overdrive series..
http://www.goodreads.com/book/show/13152.The_Angel_Experiment
But I have to admit I have not read it. I hope that helps!
Oh yea.. after reading the summary of the above book I just remembered another really good one called "The Hunger Games"
http://www.goodreads.com/book/show/2767052.The_Hunger_Games
Everybody I've recommended that to has enjoyed it immensly. It's another one
I WOULD NOT READ the summary of though... it gives too much away. It's about a TV game show that pits teenagers against each other to the death. Kind of like Survivor but without the niceness. It sounds morbid and believe me, I cannot do morbid, but it's really not. It's quite good. The Hunger Games and The Great and Terrible Beauty have been the two books that I see recommended time and time again by people who loved Twilight. They are both really good. (though nothing like Twilight at all)
I've read alot of books lately and the ones I'm listing here are the top "couldn't put down" ones for me.
Hope that helps!
P.S. I did listen to a Neil Gaiman called "The Anansi Boys" it was FABULOUS though I think it's better as a listen due to the voices of the guy who does it (FABULOUS) but it's a take off of another of his books "American Gods" which I have heard tremendous things about. It's an adult book by the author of "The Graveyard Book" which is a current-ish Newbury winner and a great read as well.