James P. Hogan's "Giants" series. Published as an all-in-one volume called "The Minervan Experiment". Not well known these days, but great stuff from the late '70s!
Lois Bujold's Vorkosigan series. Start with the Cordellia's Honor anthology (it's Shards of Honor and Barryar in one book). And don't stop until you finish Diplomatic Immunity (in all likelyhood the last book).
Further votes for Hyperion and Endymion, as well as Brin's Uplift series. I wouldn't recommend the War Against the Chtorr series as sweeping and epic, though it is a pretty interesting series...but uncompleted for a long, long time.
I did enjoy Keyes "Age of Unreason" but the ending left me highly unsatisfied, personally. But it was a great ride to get there, and Ben Franklin makes for a great mad-scientist superhero.
P.S. No one recommended Dune because the original request specifically mentioned that the poster had already read them.