We saw a lot. Jenny teases Giles (not having heard of his past as Ripper) about coffee stains and folding pages on a "first edition" that I think was an antique as well, something that would be stolen by a lot of people if they knew.
Giles said something about there being a parade if Buffy actually read a book (I think she wanted a book by Emily Dickinson to impress that one guy in season 1.)
Xander was into the comics big time. Willow as well, but probably just to have something to talk to Xander about. Gunn was also a comic geek. He was also caught having checked out a book on witchcraft, but admits it was just for the nude drawings, if I recall right. (Heh, "Reading makes our English good.")
Cordelia's attention span was so short that I doubt she'd read anything at all, but she did read something she thought could help her in the first ep of Angel.
Angel was shown reading a book, I think it gets mentioned above.
But being whimsical...
Buffy, as a teen (I'm thinking still a cheerleader before a Slayer), Katherine Applegate books like Making Out. When younger, Pippi Longstocking (to escape her parent's bickering, I'm probably projecting here). In early seasons of Buffy, I could see her into the vampire hunter books by Anita Blake, but as an adult she wouldn't have the time (unless it was assigned while she was in college, and did Willow have to act so surprised when they started arguing about a classic?).
Willow, when she tries fiction (finally), see it as The Last Unicorn as the bumbling wizard would remind her of Xander, the hag, Haggard, and such as bullies, the unicorn as herself, the knight as she wished Xander would be, and because it's in her section of the library (and I bet she liked Snoopy in Peanuts). (I could see her reading Matilda as a kid, also by Dahl, and maybe thus The Witches, but find Witches insulting as she got older.) (Today, I could see her getting into The Hunger Games, with Peeta = Xander, and also Harry Potter. Again, season 1 Willow or earlier.)
I don't know why, but I see
Cordelia reading the infamous Flowers in the Attic, and not just because it was popular (even in the 90s). Maybe because it's so different and twisted (and the lengths to keep money by oppressing kids). I kinda want to say something by Ayn Rand, but I don't think she'd have the patience for it (if she did, it would be secret), and will instead go with The Devil's Dictionary, which would appeal to her hidden cynicism and "no BS about how the world works." (Though Cordy thinking she could bargain with God to make the vampires go away makes me uncertain.) More modern version: Gossip Girl.
Hmm...thinking of a cowboy porn novel I briefly saw when I was 14, I could so see
Xander reading it (I'm assuming he found it on his passed out uncle into "booze and whores," and maybe after listening to the "music of pain," which I think is apt for old country music, and his reading fare like that would explain some awkward lines and jokes of his, plus does sound like something relatives of his would read, plus, see what I said of him above), but I'll go with The Red Badge of Courage to appeal to his macho side (and I could see the scene where one ran from a battle, and then having to hide it, compelling him to read on). But nothing in Latin, he's more magical than Willow (with him being a demon magnet and also causing books to erupt into flames just by speaking Latin, gods, as tragic as it would be, it would've explained so much if Xander was the host for Glory).
Oz: Ulysses by James Joyce. It would help explain his twisted (if fun) thought patterns, and perhaps why he accepted the supernatural so easily.
Lindsay: Grapes of Wrath
Hmmm, computers, technopaganism, monster trucks, sense of wonder...I'll throw in Christine and Night Shift (short stories about multiple things to interest her) by Stephen King for
Jenny.
Giles? Too much required reading for him. But I just now decided in my head that Giles read On the Road in high school as an act of rebellion, and was the one to recommend it to Xander. And also that Giles got his book from Ethan Rayne back when they were friends.
Spike: Poetry by Emily Dickinson. It's just too funny (and fits with William), given that the boy Buffy crushes on in season 1 was into her. Also, he drinks too much to really read anything, and I'd see him getting bored. When he needs something read, he beats up someone else to read it and give him the cliff notes.
Angel: The Metamorphosis by Dostoevsky (however,
Angelus would prefer Notes From the Undergound by the same author)
Fred: Was Nancy Drew still popular in the 90s? (Or even 80s?). We all knew who she was (even gets mentioned by Faith in that one ep), but I don't recall anyone reading those books offhand. Hmm, I could so see her reading
The Girl With Silver Eyes as a child. I see her as more nonfiction as she got older (much like Willow).
Wesley Foundation series by Isaac Asimov
Willy the Snitch - whatever his "friend" who makes "tasteful nudes" puts out. Otherwise Anita Blake, especially after it got all graphic with the sex.
Gunn - various vampire novels until he decided they were trash. Ah. The Art of War by Tzu.
