Isaac Asimov - Foundation (and the rest of the trilogy)

Robert A. Heinlein - Stranger in a Strange Land / Starship Troopers / The Moon is a Harsh Mistress

Alfred Bester - The Demolished Man / The Stars My Destination

Jack Vance - The Dying Earth

Philip K. Dick - Do Androids Dream of Electric Sheep / The Man in the High Castle

Larry Niven - Ringworld

etc. etc.

A list of Hugo Award winners[1] might come in helpful.

Another advantage of having read "the greats" is that if some critic says that new author X writes "in the style of Y" you have a slightly better idea if you might like it.

Tastes vary, of course. Personally I never got what's supposed to be so great about Ender's Game. Teen Mary Sue geek power fantasy with questionable morals. Then again, lots of people said similar things about Heinlein…

[1]: http://en.wikipedia.org/wiki/Hugo_Award_for_Best_Novel

Neal Stephenson --- Cryptonomicon. (Present day setting, but with an SF sensibility; ties into his literally epic Baroque Cycle.)

Charles Stross --- Halting State. (Investigation of an MMORPG bank breakin spills out into real-world skulduggery.)

And an oddball that folks here may not have encountered:

Mary Gentle --- Ash, A Secret History. (Starts off with interleaved narratives of a Joan of Arc figure in a strangely different medieval Europe, and a present-day Ph.D. researcher who's investigating her, and finding out that his sources literally don't say the same thing day to day. Then it gets... weirder. Quirky, brilliant, and kind of hard to find in the U.S.)

I've really been enjoying David Weber's Honor Harrington series, if you're open to military sci-fi. It's not on the Amazon site, but it's easy to get from the Baen Webscriptions site.

Iain M. Banks - "Algebraist" was a lot of fun, easily the best visualization of a gas-giant alien society I've ever read. I read "Matter" a while ago, and keep feeling pulled back to re-read it sometime soon.

For classic sci-fi, I would recommend Bester's "The Stars My Destination" and Miller's "Canticle for Leibowitz".

Don't forget to check out all the free public domain books that are available in the Kindle Store. All the Jules Verne, H.G. Wells, etc that you can eat, at no charge.

  * Heretics of Dune

  * Chapterhouse: Dune

  * Lem's Cyberiad

  * PKD's Ubik, Three Stigmata of Palmer Eldrich, and Martian Time-Slip

  * The Hitchhiker's Guide to the Galaxy

  * The Illuminatus Trilogy

Ubik is my favorite PKD book followed closely by Electric Sheep.

The His Dark Materials isn't really sci-fi so much as fantasy but it is quite a good read (though if you didn't have a kindle it might be embarrassing buying them from the young adult section, they are quite adult though).

I think a huge thing missing from your list is the Foundation series from Asimov (I recommend going in order of publishing, start with Foundation move onto Foundation and Empire then Second Foundation and more if you are into it).

My 2 cents.

If you liked "In Conquest Born" - Friedman wrote These Alien Shores, which is a true hacker sci fi, absolutely incredible.

The Book of Skaith by Leigh Bracket is a truely awesome compilation of the three Skaith novels. Leigh helped write the initial Empire Strikes back!

Almost anything by Jack Vance will be good. If you've read The Dying Earth, George RR Martin just produced a tribute called Songs of the Dying Earth with some of the best Sci Fi writers contributing.

I really enjoyed Ringworld by Larry Niven as well.And of course, the Hitchhiker's Guide trilogy in 5 parts :)

The first three Dune novels are particularly good. Dune has a tendency to get more philosophical in the later volumes (plans within plans within plans).

If I had to choose an all time favorite I would probably go with Kim Stanley Robinson's Mars trilogy (Red/Green/Blue Mars). An extremely well researched view of how Mars colonization and terraforming might proceed in a realistic way.

He also has a trilogy on the possible/likely consequences of runaway global warming (Forty Signs of Rain, Fifty Degrees Below, Sixty Days and Counting) but RGB Mars is definitely better.

Edit: "The content of Green Mars and the cover artwork for Red Mars are included on the Phoenix DVD, carried onboard Phoenix, a NASA lander that successfully touched down on Mars in May 2008. The First Interplanetary Library is intended to be a sort of time capsule for future Mars explorers and colonists." http://en.wikipedia.org/wiki/Mars_trilogy#On_Phoenix_spacecr...

Seriously, I've read these about twice a year since they came out. His Chaos series is very good too. More fantasy than sci-fi tho.

Anything by Stephen Baxter, Arthur C. Clarke, and Isaac Asimov is a must read!

- Stanislaw Lem (Solaris, The Cyberiad, His Masters Voice, Fiasco)

- William Gibson - evrything worth reading)

- Bruce Sterling

Oh, and anything by Neil Stephenson (except Zodiac).