I have the same taste in books as your wife, and I thoroughly enjoyed this series. A little different from my usuals. Your MIL might like it as well. It's definitely some easy, enjoyable reading.
Commissario Brunetti (set in Venice)novels by Donna Leon for the MIL.
Kay is probably the most underrated fantasy author. Tigana is among his best and it may be the best stand-alone fantasy novel ever.
For your MiL, I would recommend The Tourist by Olen
Steinhauer. It is widely regarded as one of the best spy novels released in the past decade but, despite that, I know few people who have read it. If she enjoys it, there's also a sequel. Edit: two sequels now, apparently. I need to get reading.
If you want to go the mystery route, I'd recommend anything by Rovert Goddard. He's an excellent British writer with something close to 20 novels. It's unlikely that your MiL has read him because those books have only recently come into print in the US.
They'll leave you alone for a month
John Adams, 1776, and many others. Take your pick.
Anything by Laurie King (but "The Beekeeper's Apprentice" is the best possible start).
Anything by Teddy White (but "In Search Of History" is a wonderful start)
Master and Commander (the first of 21 books)
Flashman (in a variety of stories; you either love the guy or hate him)
Path To Power (volume 1 of a magical biography of Lyndon Johnson)
My final suggestions:
Lee and Grant: A Dual Biography (it brought tears to my eyes)
And, of course, Manchester's Churchill (a little hero worship is not bad)
Discipline?
Fantastic books.
If so, she might like Michael Palmer and/or CJ Lyons, both of whom are MD's who write thrillers. I read a lot of what you might call "dreck". Even write some.
For "spy thrillers" somewhat off the beaten path could be Andrew Grant's EVEN. I've read that and enjoyed it. I just bought his second book, DIE TWICE. Grant's wife, Tasha Alexander is a Domer who writes best-selling historical fiction and his brother created a character called Jack Reacher.
For a kick-ass female protagonist spy thriller type, I'd recommend Taylor Stevens's THE INFORMATIONIST. James Cameron just agreed to make the movie.
I just bought a book called DON'T EVER GET OLD by Daniel Friedman. He pitched it as "the funniest books about Nazi's you'll ever read". Nelson DeMille raved about it. The protagonist is named Buck Schatz, who's an 89-year old Nazi hunter. You can't go wrong with a name like that.
...It is episodic, and well-suited for someone who would like to read 10 to 15 pages stories written like detective fiction but based on true stories of field epidemiology. As hard as it might be to believe, they are fascinating and fun.
Here it is on Amazon.
non-fiction:
habit
moonwalking with einstein
steve jobs bio
1491
botany of desire
why children succeed
omnivore's dilemma
fiction
mongoliad
day by day armageddon
wool
Olen Steinhauer's "Tourist" books. Just started the third one myself... the first two were fun
I started it this afternoon. "The tourist" and "the nearest exit" were very entertaining.
If not, get it. The Magicians by Lev Grossman is another good pick. My wife has similar interests and loves them both.
She's read book one of Song of Fire and Ice, but for whatever reason, she hasn't gone back for book two. She has read The Magicians, but I think she felt like the author loved coming up with ideas, but not following through with them, if that makes sense (it did to me), so hasn't read The Magician King.
Good suggestions though, thank you.
If she can stay interested through book 2, the rewards are there in book 3, which I consider to be one my top 5 books in any genre.
Sci-fi I love Hyperion and Fall of Hyperion. Hyperion is one of my most favorite books. If she's okay with apocalypse and vampires I think The Passage is excellent and am liking the sequel, The Twelve halfway through it.
Eric Ambler or Alan Furst. More accessible than LeCarre, just as good.
Thrones? That's my first thought. I love those kingkiller chronicles books. I've heard good things about the Magicians but haven't gotten to them yet.
It's a whodunit and very well written. The protagonist is an African American elevator inspector who gets framed for an incident, and in the process of clearing her name finds a deeper conspiracy.
medical and scientific journals for work that when I read for pleasure I want dreck and mindless reading. I really like this series, and if your MIL hasn't read it yet, she will also.
"The Alchemist's Daughter" by Katherine McMahon. (link).
I keep hoping for a sequel but nothing so far.
It's a captivating novel of the early 1700's in rural England.