Moosie, Tom, all correct!
TomH:
It is Les Miserables, and, in the edition I have, at least, it is, in fact the first line of the book, proper. (Ignoring the Introduction and Author’s Preface.)
Uke:
Nope, Through the Looking Glass. Alice’s musings on the looking glass world begin when she’s scolding the black kitten, by holding it up to the looking glass, to see how ‘sulky’ it is.
I’d give the first line of Wonderland, but someone else might wish to use it. 
Eschew Obfuscation
AW15 is interfering with my work. Can I have a hint?
While I’m here, I might as well bring the ones of mine that haven’t been guessed back to the front.
T3: ‘There was a wall.’ (I’ll be kind of impressed if anyone gets this one…^__^)
T7: ‘The telephone rang as I was chewing the final bite of the last American cheese Sandwich I ever ate.’
(BTW, checking my copy of Les Miserables, I finally note that it’s abridged. Bah! I guess the person doing the abridging cut the introduction down.)
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Arnold Winkelried:
…but when you get blue, and you’ve lost all your dreams, there’s nothing like a campfire and a can of beans!
MG5: “Miss Brooke had that kind of beauty which seems to be thrown into relief by poor dress.”
MG6: “On an exceptionally hot evening early in July a young man came out of the garret in which he lodged in S. Place and walked slowly, as though in hesitation, towards K. Bridge.”
MG7: “My lifelong involvement with Mrs. Dempster began at 5:58 o’clock p.m. on the 27th of December, 1908, at which time I was ten years and seven months old.”
MG8: “The sun rose slowly, as if it wasn’t sure it was worth all the effort.”
MG9: “I confess that when I first made acquaintance with Charles Strickland I never for a moment discerned that there was in him anything out of the ordinary.”
MoosieGirl
AW16 On Friday, June 12th, I woke up at six o’clock and no wonder; it was my birthday. But of course I was not allowed to get up at that hour, so I had to control my curiosity until a quarter to seven.
The Diary of Anne Frank
AW17 To Sherlock Holmes, she is always the woman.
Scandal in Bohemia (?), Conan Doyle
both correct.
cher3
AW19 and 20 are, respectively: “Kim” by Rudyard Kipling and “Gulliver’s Travels” by Jonathan Swift.
both correct.
AW15 is interfering with my work. Can I have a hint?
ghost story (obviously), novelette, american author.
Tengu
BTW, checking my copy of Les Miserables, I finally note that it’s abridged.
I thought so, because my copy (in french) had a different opening sentence.
Da Ace
AW18
No one seems to have made any guess for this one, so let me: Plutarch’s Lives?
correct.
MoosieGirl
MG9: “I confess that when I first made acquaintance with Charles Strickland I never for a moment discerned that there was in him anything out of the ordinary.”
Somerset Maugham, The Moon and Sixpence.
Ukulele Ike
MTS-3 has already been found.
Correct.
AW9 is easy for me, anyway, and a couple of other regular posters too. The Book of Mormon.
(Little known fact about pluto: not only a card-carrying Mormon but a former bishop!)
I’m a vegetarian once removed. I only eat meat from animals that are vegetarians.
AW15 must be “The Turn of the Screw” by Henry James. That could be counted as one of his more straitforward sentences, though.
T3: ‘There was a wall.’ (I’ll be kind of impressed if anyone gets this one…^__^)
The Dispossessed by Ursula Le Guin. (I cheated on this one, but I’m not telling how.)
MG5: “Miss Brooke had that kind of beauty which seems to be thrown into relief by poor dress.”
Middlemarch by George Eliot?
Sorry on the lateness: Absynthetic, you’re correct. And I love that book beyond belief.
That’s right!
cher3:
Portrait of the Artist as a Young Man, James Joyce
Bingo. And even though you cheated, I’m still impressed. That’s not much to go on for a cheat.
Eschew Obfuscation
I should have gotten the Joyce one. I had to read that in World Lit my senior year in HS. - Which wasn’t all that long ago -
Just to correct, AW12 isn’t really the first line of the series. It’s the first line of the first book, The Fellowship of the King. And that line is actually only the first part of Book 1. There’s a prologue on hobbits before it. Not being picky, just clarifying
When are you going to realize being normal isn’t necessarily a good thing?
Will you take a few from a guy who isn’t smart enough to answer any of them? (I did recognize maybe 3, but wasn’t fast enough to respond…)
JC1: Those who wish to win favor with a prince customarily offer him those things which they hold most precious or which they see him most delight in.
JC2: We were somewhere around Barstow on the edge of the desert when the drugs began to take hold.
JC3: The cell door slammed behind Rubashov.
JC4: What is this oozing behemoth, this fibrous tumor, this monster of power and expense hatched from the simple human desire for civic order? How did an allegedly free people spawn a vast, rampant cuttlefish of dominion with its tentacles in every orifice of the body politic?
JC5: The terror, which would not end for another twenty-eight years- if it ever did end- began, so far as I know or can tell, with a boat made from a sheet of newspaper floating down a gutter swollen with rain.
JC6: I can feel the heat closing in, feel them out there making their moves, setting up their devil doll stool pigeons, crooning over my spoon and dropper I throw away at Washington Square Station, vault a turnstile and two flights down the iron stairs, catch an uptown A train…
JC7: Among the incivilities by which nations or individuals provoke and irritate each other, Mr Burke’s pamphlet on the French Revolution is an extraordinary instance.
JMCJ
This is not a sig.
It, Stephen King?
Just a guess.
Eschew Obfuscation
JC1 = The Prince, Machiavelli. These are the opening words of the covering letter, or preface, rather than the book proper.
JC2 = Fear and Loathing in Las Vegas, Hunter S. Thompson.
JC 3: No idea.
JC 4 = It’s definitely P J O’Rourke. I’ll take a guess at Parliament of Whores (one of his best, IMHO. “Sudden unintelligence incidents” is now part of my day-to-day vocabulary).
JC 5: I think Tengu’s probably right.
JC 6: Heroin literature is quite a small sub-genre. It isn’t Trainspotting because it’s obviously American, so I’ll guess at Naked Lunch, William S. Burroughs.
JC 7 = Rights of Man, Tom Paine.
For those who don’t know what hasn’t been answered (and I’m probably one of them), here are those of mine I haven’t seen anyone guess:
DA3) It is possible I already had some presentiment of my future. Let me now add the last line, to see if that helps: It is possible that from the beginning Severian had some presentiment of his future.
DA4) Let’s set the existence-of-God issue aside for a later volume, and just stipulate that in some way, self-replicating organisms came into existence on this planet and immediately began trying to get rid of each other, either by spamming their environments with rough copies of themselves, or by more direct means which hardly need to be belabored. (Actually from the first chapter after a short “Prologue”)
Added hint: a bestseller from last year
DA7) In the nighttime heart of Beirut, in one of a row of general-address transfer booths, Louis Wu flicked into reality.
Added hint: a famous award-winning SF novel from the '70s
And some new ones:
DA9) “Tonight we’re going to show you eight silent ways to kill a man.”
DA10) I always get the shakes before a drop.
DA11) His name was Gaal Dornick and he was just a country boy who had never seen Trantor before.
DA12) Far out in the uncharted backwaters of the unfashionable end of the Western Spiral Arm of the Galaxy lies a small unregarded yellow sun. (this one’s for cmkeller!)
Oh, and I forget whose it was, but “I’ve seen through his eyes” is the first line of Ender’s Game by Orson Scott Card (which I found out inadvertently in my search for more of my own).
…but when you get blue, and you’ve lost all your dreams, there’s nothing like a campfire and a can of beans!
Da Ace,
I already had a guess at DA7. Is it not Ringworld? If not, it’s Ringworld Engineers. Both Larry Niven.
DA12 = The Hitchhiker’s Guide to the Galaxy, Douglas Adams.