When I was in high school, we lived in Germany, West Germany that is. Before the unification of Deutschland. Anyhoo, the high school I attended was a mix of the American and British school systems with a definite listing towards the American. The school library was so very teeny tiny... an unpleasant difference from the big huge libraries back in the States I was used to spending hours in. It was extremely difficult to get my book fix and I usually ended up re-reading favorites every season or more. So figure one book got read at least 4x/year and 5+ times a year at the most. Summers we'd visit the States and I would stock up at book stores, snapping up these favorites if I saw them. These were the books I couldn't live without (and in no particular order):
1) Crystal Singer - Anne McCaffery (science fiction): I practically memorized this book I read it so many times. I so wanted to learn how to cut crystal, have a symbiotic alien enhance my strength/endurance and make me practically immortal, and eat all the foods they craved during "the hunger". Nothing like sci-fi with a strong-willed female lead character successfully overcoming her flaws to an angst-ridden teenager, balm to the soul.
2) Windhaven - Lisa Tuttle and George R. R. Martin (science fiction): Another strong-willed female lead character successfully overcoming her flaws only this time instead of crystal cutting, it's flying. And while flying is made to sound really really alluring, I was never once tempted to want to try sky diving or hand gliding. I usually devoured this book endless times right after Crystal Singer.
3) The Nursery - David Lippincott (horror): This very little known gem showed me that while I thought I had it bad with my parents, they were nothing like the psycho couple the lead character ends up dealing with. I bought this book in a Vienna train station one night on our way back from a weekend school drama trip and stayed up all night on the train ride home reading it to the end. Then promptly read it again when I got home, but slower this time.
4) Gloriana - Michael Moorcock (alternate reality): This book is wonderful, it combines an alternate Elizabethan I reality, fantasy, magic, murder, mayhem, conspiracy, sex, and writing I can only compare to a huge box of absolutely delicious chocolates that no matter how much you eat, you want more. And there's no fear of calories or nauseousness. Rich and wonderful.
5) The Long Walk - Rich Bachman (Stephen King actually although I didn't know it at the time - sci-fi/horror): This gruesome dark book was a perfect high school read. Fully realized believable characters that you either cared for or hated, just like the people you were going to school with. Very detailed which made my anal-retentive heart go pitter pat. Scary in that you wonder how well you'd do in the same situation and when you'd end up... A damn fine story with an unusual unhappy ending, finally.
6) Sphinx - Robin Cook (suspense): This was actually a find that our American neighbors up the street had. They generously allowed me to plunder their book collection and while reading Nero Wolfe was alright, this book was great. Light reading for me but the story was well-told, fast-paced, and set in Egypt with strong-willed female lead character on a search for ancient treasure. (Guessing you can see a trend by now?)
7) Banners of Silk - Rosiland Laker (historical romance): I read this book to tatters, bought a new copy, read that one to tatters, and am most likely on my 5th or 6th copy. I finally found the original hardback version and that's my "good" copy (I have a back-up HB copy as well, call me crazy, I won't deny it!). Something about this book... I could say it's the writing, the characters, the dresses, the story, but that doesn't get to it. It's all those things and more. It's a book that strikes a chord and I love it and read it over and over and over.
8) The Fortress - Gabrielle Lord (horror/suspense): IF this was treated right, this book would make a great movie. But then all really good books that you stay up all night to finish and then have bad dreams about are never made into good movies because they never match what your imagination accomplishes. This book rocks, still. I finally got an out-of-print copy and it is exactly as good as I remember it. A teacher and students pitted against terrorizing kidnappers in Australia - that's all I can tell ya!
9) Anne of Green Gables series - L.M. Montgomery: I love reading this series. I read the first book to the last and cram a lifetime in a relatively brief span. Again one of those books where the writing, characters, and story just click and I can't pinpoint exactly why. Wait, maybe it's because while I'm reading it, I'm in the story and not aware that I'm reading. That's it, that complete suspension of reality.
10) Moomintroll series - Tove Jansson: Yes, these books are on the younger side but the stories, writing, and pictures are so engaging that I still find myself coning back to them again and again.
Common trend (in most of the books): strong-willed flawed female protagonist who has serious issues/dangers to overcome be it on a different planet, alternate reality, outback, in the distant past, or modern day.
What these books did for me in high school (and do so even today): due to a combination of great writing/great stories/great characters/great details = suspended reality and made me leave my life for a while never once feeling like I was reading a story, but actually seeing it unfold before me (granted in my head, but still).