The whole trilogy was great, and I was sad when I finished The Children of the Sky because there weren't any more books set in that universe left to read.

Another space opera I felt the same way about is Peter Hamilton's Commonwealth Saga. There's also a trilogy and some other novels set in the same universe. 99% of the fiction I read is space opera, and the Commonwealth universe is definitely my favorite. So action-packed and enthralling, couldn't put the books down. As a matter of fact — it's been a few years since I've read them, and I'm almost done with Lords of Uncreation, so I think I may read it again :)