Vurt is probably my favourite sci-fi book: lyrical prose, a great sense of place (a remixed Manchester) and a real feeling of poignancy, unusual for the genre. I would avoid the follow-up (Pollen) though, personally found it to be an utterly unreadable experiment with language at the complete expense of clarity and plot.
The only other sci-fi authors I've been able to read since I was 15 (without feeling faintly ashamed of myself anyway!) are William Gibson and Iain M Banks. Re the former, his debut, Neuromancer, is possibly still his best, though I really liked his most recent effort, Pattern Recognition (though it's not really sci-fi - set now'ish). Re the latter - Consider Phlebus or The Player of Games are good introductions to "the culture" (Excession and The Use of Weapons are also pretty damn fine).
Off the sci-fi, the best new'ish book I've read for years is probably Cloudwritten by David Mitchell - several interwoven stories set mainly in the far east. Clever and great fun - it absolutely flew by (which surprised me as I normally find Booker prize type stuff to be a bit onerous). You also get to painlessly learn a bit about Japan, and China's cultural revolution along the way... which is nice.
All time classic recommendation: The Great Gatsby by F Scott Fitzgerald. Just staggeringly beautifuly written - and the only one of his books where I had any sympathy whatsoever for one of his characters (as far as I can tell the rest of his stuff revolves around wealthy, unpleasant types who are drunks as an alternative to working - rather than because of it).