I mostly read science fiction or history, although I was a big fan of John Barth back in the day (especially Chimera and Letters). I have a fond memory of discussing JB on the chairlift rides during a fill-in-your-tracks storm at Stowe about 25 years ago. Just a chance ride with a fellow fan, no idea how it ever came up -- we spent the afternoon skiing and talking.
A non-fiction favorite from ten years ago - Salt by Mark Kurlansky. It started a fashion for historical anecdote around a loosely coupling theme, by Kurlansky and imitators. Googling I find that some of his books I thought were follow-ups were actually written earlier (Cod, The Basque History of the World). Salt is the best, I think.
When I was cleaning out my office I found another old favorite, and actually re-read a few chapters: The Birth of the Modern by Paul Johnson. It is about how developments in the early 1800's led to a recognizably modern world.
Some science fiction favorites: Everything by Neal Stephenson. Reamde is a great, wild read. I lent it to my son, and he said "Wow, I didn't see that coming." Cryptonomicon is probably his classic. I loved Anathem, but its a bit philosophical for some people. The Baroque Cycle (three 1000 page novels, Quicksilver/Confusion/The System of the World) is for the already converted. It has a large number of interlocking plot threads, some of which disappear and then come back hundreds of pages later. I was a bit dismayed by the ending though -- I thought back and said to myself, "Hey, that bit with Isaac Newton at the beginning of the first book... how does that tie into everything?"
Another big favorite - Ian M. Banks "Culture" series. Six or seven long novels. The best are probably Matter, Use of Weapons, and The Hydrogen Sonata.
I just finished Michael Flynn's January Dancer thru Razor's Edge series. Good space opera to read on the stair master at the gym. His best work is In the Country of the Blind. The basic premise is that the standard "you can't beat the market" wisdom is a cover for the secret cabal that has been beating the market for hundreds of years with a primitive form of psycho-history. The conspiracy starts to unravel in a series of double crosses and adventure ensues.
More history - the Nancy Goldstone medieval histories are fun, easy-to-read character-driven histories with an emphasis on behind-the-scenes maneuvering by the women in the story. They include Four Queens (4 sisters all became queens of important powers), The Lady Queen, and The Maid and the Queen (Joan of Arc and the people who manipulated her.).
Another I got a kick out of because it is about a time and place I didn't know much about, James Romm, Ghost on the Throne about the aftermath of Alexander the Great's death.