Both of those were already mentioned, so let me drop a recommendation for something new - Worm, the first (and absolutely massive) book in Wildbow's Parahumans series. Iirc it's longer than all 5 published ASOIAF novels combined, so it's a big commitment, but that length moves through a ton of different arcs. It's centered around a "superheroes" kind of scenario with a level of analysis and thought that'll tickle the fancy of certain kinds of nerds. The main character's power is to control bugs - and it's a lot of fun to see the author make that seemingly lame power into something incredibly useful and lethal. It's just a fun read overall, lots of room to nerd out about it. I haven't read the sequel yet, but I've read good things.
Also, though they're more mainstream, Greg Egan and Ted Chiang are some of the best spec-fic / sci-fi authors I know of, and do a similarly great job of breaking down interesting concepts into compelling stories.