I just finished Vacuum Diagrams by Stephen Baxter yesterday. Frickin' delicious SF; it takes place from like 3500 AD to 500,000,000 AD, the end of the baryonic universe after the godlike Xeelee's conflict with the dark matter Photino Birds. The writing is just enchanting, it even supersedes Larry Niven, who for a while I considered the king of SF. Other SF I'm into include the Known Space universe by Larry Niven(obviously), and the Eschaton series by Charles Stross, though I've only read one of the two books in it, Iron Sunrise. I do consider it to be the best hard SF book I've read, but it depends on what you're looking for. Iron Sunrise delivers a very dark and gritty, almost cyberpunk-like plot, while Known Space deals more with fanciful theoretical physics and alien species.
For fantasy I really only like Terry Pratchett's Discworld series and Phillip Pullman's His Dark Materials trilogy. Discworld is some of the most well-made and hilarious stuff I've ever read, though His Dark Materials is a whole different experience. The concepts Pullman introduces with his multiple universes and epic plot kind of tower above Discworld's offerings, but like Eschaton and Known Space, it depends on what you're looking to read. The Amber Spyglass, book three of His Dark Materials, is the only story of any kind to evoke a strong emotion from me other than laughter. The end actually had me depressed and mopey for a good three hours. But all the books I've mentioned are worth a read.