I would suggest checking out Dan Simmons. He's like Neal in many ways (lots of world building, interesting scifi), but I think a better writer and story teller. I picked up Hyperion based on a review of Seveneves, which suggested the third part was a pale imitation. It and Ilium are amazing.
+1 for Dan Simmons and especially Hyperion. It is more what I'd call "science fantasy" in my personal classification system, but it's an amazing book, in my top 5 for sure.
Thank you both for the recommendation - Hyperion's now queued up on my ebook. Sounds like the first pair of novels are more highly regarded than the second pair?
I think if I had to rank them I'd say Hyperion is top-tier, the sort of book I can quote from even years after reading it. The others are merely excellent sci-fi novels. I don't know how I'd rank the second book against the last two; they're fairly different and I enjoyed them all.
Hyperion is the best of the books in my opinion. One of my favorite books of all time. The Endymion books are a different story set in the same universe, and can be skipped if you want.