The Stars my Destination is probably one of my favourite sci-fis. It's basically the count of Monte Cristo but set in a feudal capitalist future. It has a strong claim of being a progenitor for Cyberpunk, and it's packed with all sorts of high concept ideas that get tossed aside as soon as they wear out their welcome.

And if you want something really meaty, go for the bas-lag trilogy by China Mieville starting with Perdido Street Station- probably my favourite fantasy series.