Dune by Frank Herbert. I tried reading Asimov's Foundation several months ago, but just couldn't stick with it. Dune has a similar scope, with lots of characters, history, rich and detailed political and social dynamics, but I am enjoying this much more.
While taking a break from Dune, I read Calculating God by Robert Sawyer based on a friend's recommendation. The whole story seemed like an amateurish platform for the main plot, which is a conversation between an alien and a human paleontologist about the existence of God. Some of the standard arguments for and against which I found good reading, but the rest of the story was unnecessary and didn't do anything for the main plot.