Have you looked at the SF Masterworks series of books for inspiration? Loads of books from both old and new authors. Plenty already mentioned in the series: Frank Herbert, Ben Bova, Philip K Dick etc. Also Frederick Pohl and Alfred Bester and plenty of others.
However I would give Timescape by Gregory Benford a miss. The only book Ive had to give up on in recent times as it was just so damn boring (although I am getting close with the Woodcutter by Reginald Hill <stifles yawn> But thats not Sci-Fi).