Oh man, I've read the Company Series by Kage Baker and enjoyed them very much. They're not necessarily bubble gum sort of fiction, but compared to Kindred or Parable of the Sower they're pretty light reading.

I don't think this is space opera, but The Sparrow by Mary Doria Russel is absolutely fansastic, as is it's sequel Children of God. I almost cried with joy when I found out there was a sequel, that's how much it moved me. They're definitely more toward the harder end of science fiction with the space travel and all, but they raise some huge social implication type questions. And they're just fantasic books anyways.