The Gap Into Conflict question

If you like the dark gritty side of this book, you might try the anything from the Revelation Space Universe by Alistair Reynolds (although, perversely, I wouldn't start with the first book, Revelation Space).

If you like wide, galaxy spanning opera you might try Kevin J Anderson's Saga of Seven Suns.

Hope this helps :)

Try the Dune series by Frank Herbert. It's as complex, perhaps not quite as tightly written, but certainly is 'galaxy spanning space opera'. The Gap series is, however, my favourite.