The Hydrogen Sonata - Iain M Banks
Seconded. That's the last SF novel (and the penultimate novel) he wrote before cancer. The two drone ships by Space X are named after spaceships in the Culture novels and legions of fans wept when they found out that there wouldn't be any new works in that universe.
Note that when he writes as Iain Banks, it's "non SF" stuff, and Iain M Banks, it's SF. It's sometimes hard to figure out the limit between the two.
Neptune's Brood - Charles Stross
It's a sequel to an early novel (Saturn's Children), but a stand-alone work. It's one of those novels that get praise by nobel-prize economists (how does the economy of a non-human galactic-level civilization limited by speed of light works? Answer: with very big scams).
I would recommend anything by Stross, by the way. He writes well, deconstruct most expectations, and his novels are always on hardcover preorder from me.
In particular, you have two major series by him:
The Merchant Princes: A deconstruction of the Parrain's Daughter myth. The core story is that Myriam, freelance economical journalist from Boston, finds that she's able to travel between worlds... and she's the lost heiress to basically one of the six interdimensional Mafia clans. She's of course abducted back to her family. Stuff happens. The multiverse will never be the same.
(can't go further without spoiling)
It's a complicated story; it was originally marketed as fantasy because of contractual obligations; he couldn't write a SF story. So the first 4 books were labeled as fantasy by Tor, the last two jackets say "SF" (but it's really SF from the outset, not some urban fantasy stuff). He intended originally a trilogy, but his US publisher balked at the doorstop first novel, so each book got split in two. The omnibus editions I linked are closer to his original vision.
Caveat: After a 7-year break, he's publishing a new trilogy (of only 3 books, not 3x2...) that has the informal subtitle "Merchant Princes: The Next Generation". First book is coming early next year.
The other ongoing series is
The Laundry Files: Fantasy-SF blend again, based on the premise that Math is Magic (do too much advanced math, invoke extra-dimensional creatures) and H.P. Lovecraft is suspected of having had illegal access to classified information.
(just finished The Nightmare Stacks, his latest book in the series which came out two weeks ago or so. A bit too obvious, though; you know how it's going to unfold and end roughly by the first third of the book. Still enjoyable)
The entire series revolves around agents of the Laundry, a british department tasked with managing magical stuff, as they gear up for the time when The Stars Align and Joe Average becomes capable of opening portals to dimensions best left alone. The main protagonist is "Bob Howard" (a pseudonym, no secret agent will ever give his real name, specially when Real Names have Power), a too curious computer geek that got an offer he can't refuse (join or be executed as threat to the Crown). Features heavy geek humor, with passages like:
Theories on her deviant behavior revolve around a possible sociopathic schizophrenia, an extensive capacity for doublethink and overexposure to Windows 2000 Directory Services.
As usual, he heavily deconstructs classical tropes, with a good dose of spy novel stuff. It's not often that you see basically the Batmobile being necromantically powered by the bound souls of murdered dolphins.
Series is ongoing, 3 books still planned (after a diversion for the last two books that feature other main protagonists, he'll be back to Bob in his new job, whose title I can't give because spoil).