Cherryh's Faded Sun series, one of my favorites. The Faded Sun:Kesrith, etc. Check out the specific titles online and be sure to start with the first one. Stand-alone books include Demon Breed by Schmitz and Monument by Lloyd Biggle, Jr. And I usually don't go in for historical books, but I loved Michael and Jeffrey Shaara's books on the Civil War, such as Gods and Generals and Killer Angels. Tremendously readable, great stories, absolutely historical but filled in with fictional details to make it a great story. I went on from there to read Jeffrey Shaara's Mexican-American War series, WWI series, and WWII series. Amazing books. I learned more about the Civil War in ten pages of the first novel than in all my years of school. Finally, epic novels includes Michener's books, fictional epic history novels, each focused on a place, from Mexico to Hawaii to Massachusetts to the South Pacific to... fill in the blank.

You've read all of Tolkein's stuff? The Silmarillion?

I'm interpreting the intro as meaning he is looking for science fiction, not fantasy.

Neal Stephenson - I particularly liked Crytoponomicon and Snow Crash but all his stuff is good.

Julian May - Galactic Milieu series

If you like military science fiction go for the Lost Fleet by Campbell or The Posleen War Series by Ringo.

@Muju

Thanks for the suggests (I've actually already read some of those), but I'm looking for particularly an epic Science fiction series.

Also go read the Starship Troopers book. It is awesome, way, way better than the Film.

Oh epic it has to be? Then you should totally read Otherland by Tad Williams.

If you like alternative history, Turtledove has some great series (Lee gets AK47s in the civil war).

p.s. you're showing your age, Ab. Have you read Riverworld by Farmer?

I've read Starship Troopers; I personally prefer the Forever War but, it's good, too.

Hm yeah, the Forever War was nice aswell. Did you read Armor?

No, I"ve not read Riverworld, nor Armor.

Abgab, that Faded Sun series is very good reading--a tremendous mix of hard sci-fi and culture clash stuff, plus a long, long historical view.

Oh yeah, I forgot about Otherland. I second that one.

I think i don't even have to suggest it here but just because i like the series so much: Honor Harrington by Weber. One of the best long running Scifi Series that are around.

Here's a "thank you", Ab, for moderating:

Top 15 Sci Fi book series (from 15 to 1)
http://listverse.com/2008/03/25/top-15-science-fiction-book-series/

Vorkosigan Saga
Lois McMaster Bujold

The Book of the New Sun
Gene Wolfe

Hyperion Cantos
Dan Simmons

The Space Odyssey series
Arthur C Clarke

The Culture
Iain Banks

Rama Series
Arthur C Clarke, Gentry Lee

Dune Series
Frank Herbert

Heechee Saga
Ferderik Pohl

The Hitchhiker’s Guide to the Galaxy
Douglas Adams

Ringworld
Larry Niven

Ender’s Game Series
Orson Scott Card

Future History Series
Robert Heinlein

Barsoom Series
Edgar Rice Burroughs

Lensman Series
E E Smith

Foundation Series
Isaac Asimov

And thanks to everyone for their suggestions, I'm printing all of this and heading back to the library!

Here is a link for Armor (really worth the read):
http://en.wikipedia.org/wiki/Armor_%28novel%29

One for Harrington:
http://en.wikipedia.org/wiki/Honor_Harrington

And for good measure i'd also suggest Old Mans War by Scalzi, 4 books, i liked them a lot:
http://en.wikipedia.org/wiki/Old_Man%27s_War

I discovered Armor because Orson Scott Card suggested it in an author preface to some anniversary edition of Ender's Game.

I really like Perdido Street Station by China Mieville.

Ooh Hyperion Cantons, the one Indy posted there, it's awesome. And it really fullfils your wish for epic entertainment.

Have you read any Walter John Williams? He is one of my favorite SF authors. Each of his novels is pretty different. Of his works, in particular I'm suggesting the epic trilogy Dread Empire's Fall, consisting of The Praxis, The Sundering, and The Conventions of War. Each book is pretty hefty.

John Steakly (I think) wrote Armor, which is awesome. Great to read with/after Starship Troopers.

I'm going to second Partysane's recommendation of Old Man's War by John Scalzi. I don't often read sci-fi, but when I do, I prefer Scalzi. What other sci-fi writer puts old-order Mennonites in space?

Haha yes, one of the Mennonites is even called Yoda (Hiram with first name) he dies a nice death..

I believe that was Yoder, not Yoda.

I second the recommendation of Larry Niven's Ringworld series (Ringworld, Ringworld Engineers, Ringworld Throne and Ringworld's Children).

I would add the rest of Niven's Known Space stories (which effectively end with the Ringworld series) - World of Ptavvs, A Gift from Earth, Protector, Man-Kzin Wars II, Neutron Star, Ringworld. You'll notice that the technology level increases from story to story if you read them in this order.

Peter F Hamilton's series "Pandora's Star" and "Judas Unchained" is quiet simply brilliant.

Richard Morgan's "Kovacs" stories a mind blowing "Altered Carbon", "Broken Angels" and "Woken Furies".

I've read Ringworld. Is it worth finishing the series?

Yes, though if I was giving the books marks out of ten I'd give them:-
Ringworld - 10
Ringworld Engineers - 7
Ringworld Throne - 8
Ringworld' Children - 10

I hope you've read the other Niven books I recommended too.

Zelazny, "Lord of Light". Indian gods in outer space. Not a series, but totally epic.

The only other Niven book I've read is Mote.