I feel like a grumpy old guy, but I feel like a lot of concepts in Death's End have been done better by other authors, especially the out-there ideas - I don't want to list them, lest I spoil things for people.

Given that Alex above has thrown in some recommendations, based on your interest in the ideas here I'd throw in:

just about anything by Greg Egan; if you want crazy physics, go for Clockwork Rocket. If you want more humanity, go for Diaspora. anything from the Xeelee Sequence by Stephen Baxter. Ring is a good start; Vacuum Diagrams is a good collection of stories. (None of these are happy stories.) Blindsight, by Peter Watts