I have read relatively little "classic" science fiction, the earliest story of which is War of the Worlds, by H.G. Wells, published in 1898. From what I recall, it is one example of Victorian/Edwardian-era literature that doesn't "feel" like something from that era. It doesn't read like Charles Dickens, for instance.
Nothing comes to mind for the decades of 1900, 1910, 1920, 1930, but for the 1940s, there is The Foundation, by Isaac Asimov. According to Wiki (as of 6 September 2008), the stories within Foundation were published from 1942 through 1950. The "feel" of the book is like pulpy, comic-book science fiction, the kind that you can imagine, with characters talking like snarky New Yorkers.
The overall concept is bold: The Galactic Empire is failing, slowly but surely, and one guy has figured it out. Hari Seldon, psychohistorian, has modeled civilization mathematically, and has seen the future, mathematically speaking. He arranges the creation of a Foundation (two, actually, but that is mentioned only once in the first book, and again once or twice in the second book) to preserve the scientific knowledge after the Empire falls.
Naturally, the powers that be at the Empire do not like the idea of someone spreading word that their government system is going to fail, and that there is nothing that anyone can do to stop it. This doesn't stop Hari, who tells a young protege, Gaal Dornick, about his work. The suspense builds; will Gaal be able to create the Foundation? Will someone from the Empire try to stop them? Will anyone not talk like they have an attitude problem? All that and more, just turn the page to read the next chapter and--
--fifty or so years have passed. What happened? Well, apparently, the Foundation was established, and it has a bunch of scientist and bureaucrats arguing. At this point, I had a hard time caring. What happend to Hari and Gaal? Who are these new people? Why are they all so sarcastic? There is a crisis or something, political parties form, and something like a revolution occurs, and so then you turn the page and--
--not again! Sixty or so years have passed, another crisis, new characters, new names, no new attitudes...
And so it goes for the rest of the book. The reader goes through a history of the first two or three centuries of the Foundation itself, faster than one goes through American history in fifth grade. Imagine reading the personal accounts and meetings of Thomas Jefferson, George Washington, and Benjamin Franklin. Then, just as Washington refused to be elected to a third term, you turn the page and--
--Kansas is bleeding! Now you have Congressmen beating each other up, and South Carolina secedes and...what is going on?
The point is, one can excuse the reader for thinking that the story of The Foundation is really the story of the crises of the first Foundation. As if nothing of interest ever happens on Foundation in between the crises. To top it all off, near or just after the resolution of each crisis, a scheduled hologram appearance of Hari lets viewers and the reader know that he, Hari, saw the whole thing, and that such-and-such should have happened.
The reason for this story arrangement is that The Foundation was not published as a complete body of work. Asimov wrote each crisis as an independent story. This would explain the near-zero character development that occurs. By the end of the book, I could have cared less about what happened to the Foundation or its residents, especially since Hari reminds everyone that he saw it coming, but won't tell you what's going to happen next, since that would violate one of the laws of psychohistory.
So, onto the second book, Foundation and Empire. This book is actually much more interesting, featuring things like character development. This book is also actually two stories, one after the other. They are both crisis stories, but the reader follows two or three characters as each crisis unfolds over months and years. This in-depth approach actually lets the reader know more about what happened before each crisis, in a casual, non-encyclopedic way.
The first story is about a General, named Bel Riose, who thinks that he can take on Foundation. Why? Just because he has been successful in the past. By this point, the Empire (still falling, three or so centuries after Foundation was started) has lost technological superiority over the Foundation, despite having a much larger population. What is comedic about this story is that one of the people that Bel consults, tells Bel that he will fail. How Bel will fail is not known exactly, but since his success would mean the demise of the Foundation, Bel will fail. Foundation cannot fail, which means that anyone who tries to destroy will somehow not succeed.
So much for anyone.
What about anything?
The second story in Foundation and Empire is so far the most interesting story in Foundation. Two newlyweds, Toran and Bayta, meet a performing jester, Magnifico, and take him with them on their travels. Meanwhile, a civil war is brewing between Foundation and the surrounding planets. And then, something, known as the Mule, begins to take over the planets. The Mule can do something no one else can -- manipulate other people's emotions. Mostly, in a negative way. He kills morale, brings people over to his side, and sort of saunters his way to power.
So, Toran and Bayta find themselves on the run with Magnifico and a scientist, trying to find ways to defeat the Mule. After an encounter with a mind-controlled agent of the Mule, and a run-in with other unsavory characters, Bayta points out one fact: after all their running, why are they the only ones who haven't fallen under the power of the Mule?
Overall, if you can get past the first book, the second one is pretty good. Foundation encompasses a whole series of books, making reading the entirety of the story as daunting as reading The Baroque Cycle by Neal Stephenson. If you have the patience, it's worth it.