Yeah, read the Song of Ice & Fire series. I don't normally like those kinds of books but both my husband, my best friend and I all love them. There are tons of really good characters and the plot twists always surprise you (but they're not cheesy).

I finished the third book, A Storm of Swords, about a week ago. I already have the 4th one but I'm probably going to wait until Christmas time to read it.

I haven't read them yet, but my husband loves Snow Crash, Quicksilver, and Anathem by Neal Stephenson. They're all science fiction.

Here's a list of winners and nominees for the Arthur C. Clarke award. That should give you a decent list of good sci-fi books. All the Neal Stephenson books I listed were either nominated or won the award.
http://en.wikipedia.org/wiki/List_of_Arthur_C._Clarke_Award_Nominees