Manifold: Space, by Stephen Baxter.
BIG book - full of ideas, spanning eons. Oddly, I picked this up, though it is the second of the "Manifold" trilogy. He does a good job of isolating the book from the other two - eventually I may read them, but I'm not in a hurry. I do have his alternate history "Voyager" to read next. This one was good, but.. I don't know, kind of overly filled with BIG scope, BIG ideas and so on. An interesting answer to the the Fermi Paradox, though.....

The Free Lunch, by Spider Robinson.

Fun book, nearly a "juvenile" aside from some adult references and language. Set in a DisneyLand-esque "DreamWorld" of the future, and revolving around Mike and Annie, two who have managed to leave the real world to take up permanent (and unofficial) residence in DreamWorld "Under". How do they foil the plots of an evil competitor, owner of "ThrillWorld"? What is the mystery of the EXTRA trolls seen leaving Dreamworld every day? As one who has been to Disney parks more than a few times, and even toured "under" the Magic Kingdom in Florida, this is a fun story - part wish fulfillment for anyone who'd like to live IN the parks. Nearly calls for a sequel - but maybe better left to the reader to imagine.