If you wish to follow my suggestion to read screenplays in order to learn to write screenplays--or if you just wish to read them as a piece of writing--here's a list of ones I think will give you a good taste of what fine screenwriting can be.
You should be aware that screenplays are available either in published book form or downloadable from legitimate screenplay websites on the internet. Most downloadable screenplays are free, some require payment and some are sites that will sell you hard copies of the original film or TV script that are then mailed to you once you've paid for them.
Here's a suggested list of PUBLISHED SCREENPLAYS--not in any particular order:
Three Films of Woody Allen - an interesting collection which includes Manhattan, co-written with Marshall Brickman. These scripts are notable because Allen if he's writing alone or with a co-writer includes a lot of stage directions and parentheticals which most writers would not include and most actors and directors would resent reading. It's kind of like directing on paper. But since Allen is the director, I guess he doesn't care. So read these for the story, the characters and the dialogue, but I wouldn't recommend following the format too closely if you want to write your own script.
Hannah and her Sisters - a wonderful screenplay, but with the same caveat as above.
Broadcast News - James L. Brooks is one of my heroes. He began writing television in the 60's for shows like Room 222 and The Mary Tyler Moore Show. He's a journeyman writer--like myself--and eventually found the means to write, produce and direct feature films. I'm not a fan of his adaptations like Terms of Endearment--because I don't care for the original novel--but Broadcast News is a terrific screenplay. It is also unconventional in that it focuses on three main characters, not one. What it does so well is something all good screenplays should do: take us into another world and show it to us authentically. Brooks takes us inside the world of network news and reveals it to be funny, shallow and exciting. His characters are so real and yet not everyday but original and eminently watchable.
Five Screenplays by Preston Sturges - the master of screwball, cynical comedy. Again written as vehicles for him to direct, so don't follow his format. They also use a very specific old Hollywood studio system format that is no longer used, so try and read through that and see the story and characters shining through.
William Goldman: Four Screenplays - another master screenwriter famous for opining that "Nobody Knows Anything." Except he knows how to write a terrific screenplay. One of the giants.
The Shawshank Redemption - if you can--and as screenwriter Frank Darabont urges the reader to do in his introduction--read Stephen King's original novella first, then see how Darabont brilliantly adapts it to film. But really, the credit must go to King first for his story. Darabont was smart enough to know not to mess with it.
American Beauty - an original masterpiece by Alan Ball who went on to create a little TV show called Six Feet Under. Won an Oscar and if you read it, you'll see why it deserved to. You'll also notice that it differs significantly from the finished film and there's a huge lesson in that as well.
Sunset Boulevard - Billy Wilder is a god of the Hollywood film and this screenplay embodies the hallmarks of great screenwriting: an original idea. He also does what Brooks did with Broadcast News and that is take the reader/audience into a world they would not otherwise know: the demented mind of the silent film star played by silent film star Gloria Swanson. I can't help believing that there's more truth than fiction to this.
Five Screenplays – Harold Pinter - For a master class in writing as poetry, read Pinter's scripts. Perhaps the "leanest" screenwriting I've come across, he proves that a picture doesn't need a 1000 words. A well-chosen ten is usually all Pinter needs.
Platoon/Salvador - Oliver Stone's diptych of Americans going mad in foreign wars of their own making is diametrically opposite to Pinter's sensibility. Stone wears his heart on his sleeve and his writing explodes off the page.
A Neil Jordan Reader (includes screenplay for The Crying Game) - Neil Jordan was one of my teachers at the Canadian Film Centre, so there's a personal connection for me. His script for The Crying Game is a revelation. Originally titled The Soldier's Wife, apparently the revelation that Dil was really a man--hopefully you knew this!--didn't come until several drafts had been written!
Memento & Following - remarkable for the reverse order scene structure of Memento. Following is his first screenplay, which apparently was shot over a couple of years on weekends. Reading it, I realized you don't shirk on good writing just because you don't have the money to make the movie.
The English Patient (screenplay) - another personal connection for me, having attended the Canadian Film Centre with Michael Ondaatje who wrote the original novel and taught with the late Anthony Minghella who adapted it for the screen. What's most remarkable for me is that Minghella claims that once he began work, he referred to numerous books on the desert, World War II, Africa--the one book he didn't refer to was the original novel! I disagree with the direction he took in diminishing the Sikh sapper's story in his film version, but otherwise, he made dramatic what Ondaatje made poetic.
Best American Screenplays vol 1-3 ed. Sam Thomas - a set of American screenplays in 3 volumes that form a basis for understanding the form. Too many important works to list here. I cherish my copies as if they were the Dead Sea Scrolls.
The Apartment (in a collection with The Fortune Cookie) - A pair of Billy Wilder-I.A.L. Diamond comedic masterpieces.
Chinatown (available in collection with 2 other Towne screenplays) - Having taken a master class given by screenwriter Robert Towne, it's fascinating for me to see his personal sensibility infused in the writing of his classic screenplays. However, credit must be given to director Roman Polanski for pushing the ending of Chinatown to the darker version we know from the film.
The Collected Works of Paddy Chayefsky, (4 volumes) - No one can write more passionately, no one clearly cared about his characters more than Chayefsky. The fact that his scripts started as TV shows in the 50's is mindboggling given what usually passes for TV writing today.
A Fish Called Wanda - Written by John Cleese and Charles Crichton, this screenplay is incredibly lean in the writing and incredibly funny in the reading.
My Beautiful Laundrette and The Rainbow Sign by Hanif Kureishi - The vanguard of new British screenwriting. I had written my first TV movie for CBC before this came out--a multi-racial romantic comedy and realized I'd been put to shame by Kureishi's groundbreaking and brave work. Humbling for me and an inspiring piece of writing for anyone from a cultural background other than English or French who wishes to write about what they know.
There's plenty of other screenplays to read, of course. This is really just a sample I culled from my own personal library. Many will be out of print, but most are available at the Library.
If you haven't seen the films that these screenplays were made into, try not to! Read the screenplay first, THEN screen the film. It's going to give you a better idea of the power and responsibility the screenwriter must embrace in evoking a film that hasn't been made. Then watching the film will reveal how much of the movie was actually on the page. (Doing this will also demythologize the auteur theory that gives all the credit to the director!)
Enjoy these screenplays. They're blueprints for movies that hadn't been made when they were written--and works of art in their own right.