The Neuromancer trilogy by William Gibson is pretty decent if you haven't read them yet. If only to see the origins of The Matrix and cyberpunk.

There's a series of books called 314 by A.R. Wise that I recommend to everyone. There's three books in the series and book one is based around time travel but mostly focuses on horror elements. I know that's not what you were asking for but the reason I mention it is because each book gradually focuses more and more on science fiction aspects. As far as complexity goes, the writing is passable but nothing more. The story and subtle changes throughout the world that the books exist in is VERY complex though. I've read them at least four times over now and am still picking up on some shit that I missed the first time. Lot's of going back a few pages to see if some character actually said what they thought they said. 

I suggest anything by Terry Pratchett any time I can. More his Discworld series. Light Fantasy with a hefty dose of satire.

My current favorite series is the 1632 series by Eric Flint. The universe has gotten so big, there's a monthly short story anthology by various authors that's set in it, called the Grantville Gazette. It's based around a blue-collar area of modern-day West Virginia (If I remember right) being transposed in space and time with an area of Germany in (surprise!) 1632. The characters are great, the writing is great, and there are plenty of historical tie-ins that you wind up actually learning about the era as well.

The Garrett, PI series by Glen Cook is interesting. I randomly grabbed a three-novel anthology from it at a flea market and loved it, but haven't checked out the series any further. Intend to, though.

I'll have to check my shelf and update this some other time. I read so much, I tend to forget what I've read and enjoyed.

This isn't a very original recommendation but H.G. Wells is really fucking good. I know that most people know about him and specifically "War of the Worlds" but he has a LOT of solid novels. "Time Machine" arguably started the whole time travel thing in books and does it better than almost any other. "The World Set Free" conceptualized the atomic bomb and even gave it the name it has. I would consider it a fantasy novel too, which I do believe is what you were asking about. 

If you're into graphic novel series Neil Gaiman's The Sandman is a mythic work of art.

GanjaGoblin said  I forget the name of this book and I've been wondering what its called. I'd like to read that again.   
 

"All Summer in a Day"?

http://en.wikipedia.org/wiki/A.....r_in_a_Day

Ive never wanted to talk about Stephen King more in my whole entire life....FUCK

krunkazphunk we are perfect for each other man  I will even let you stay the night in my camper and man it will be real fun

krunkazphuk said
I think I just threw up in my mouth a little bit.

If I'm as intelligent as I think I am, I think that means she likes ya, man.