Greg Bear (Eon, Queen of Angels) comes to mind. If you're looking for something off the beaten path, try Neil Gaiman (American Gods, Good Omens-with Terry Prattchet).
The Mars series by Kim Stanley Robinson is a daunting task, but has a lot to recommend it.
Thanks, I will check them out. I read Greg Bear, but never Neil Gaiman. I almost finished second book of the Mars series, and then took some time off. I bought all, so I'll return to them. Lots of good ideas and interesting, even if left-leaning pondering on the economy of so far removed colony.
Now you've done it. There's so many SF fans here that this thread will grow and grow.
Here's my recommendation: Alistaire Reynolds "Revelation Space" He's a PhD physicist and does a very good job of weaving current trends in cosmology with and intersting premise why we are apparently the only intelligent life in the galaxy.