Anything by Jane Austen. Unfortunately there are too few.
Anything by Douglas Adams.
If I’m feeling romantic, or if I’m feeling a distinct lack of romance, Romeo & Juliet.
I like to reread the Sherlock Holmes cases.
The short stories, not the books, since the books necessarily have a lot of filler - atmosphere and chase scenes and dialog with suspects that don’t have anything to add to the case.
Also, I’ve found that the later cases, the ones after his “return from death” were just adventures and police procedurals, rather than the brainy first books.
And of course I like to read the many books that analyze Sherlock and Doyle.
Many of my favorite, comfort-books are already on here!
Lonesome Dove tops the list
Midnight in the Garden of Good and Evil
The World According to Garp
To Kill a Mockingbird
Addie Pray (also sometimes titled Paper Moon; part of the book was the basis for the movie)
The Stand (I miss Stu, too!)
Gone With the Wind
Sophie’s Choice
Cold Mountain
The Last Unicorn
Neverwhere
The Princess Bride
Lord of the Rings (my own personal ‘good parts’ version)
Till We Have Faces (… obviously)
Last night I re-read Angel-Seeker, by Sharon Shinn. Her books are so gooey and overly romantic, and yet strangely compelling.
Jane Austen
Georgette Heyer
Mary Stuart
Agatha Christie
Josephine Tey
Ruth Rendell
PD James (some)
Bill Bryson
LOTR (rarely)
Harry Potter books
Lord of the Rings and The Last Unicorn are high up on my comforting to re-read list.
Any Discworld book, The Lord of the Rings, Dave Barry.
Those are my favorites too; I reread them every couple of years or so.
I also like:
Nero Wolfe
Terry Pratchett
Heinlein (mostly the older “juvenile” novels)
Dean Koontz (yeah, he’s cheezy but they’re fun)
Stephen King (older ones only)
Pride and Prejudice - it never gets old for me. I still giggle and grin and am generally happy with the world when it ends.
Pratchett & Brust novels are generally good for quick reading. From time to time, trashy romance novels.
Wodehouse for laughs.
Effinger’s A Fire in the Sun. Second book of a trillogy, and the only one that I actually own a copy of. Highly recommend it- ‘old school’ cyberpunk set in the middle east.
Some of mine have already been mentioned, but other comfort books include:
I Capture the Castle by Dodie Smith
In This House of Brede by Rumer Godden
The Betsy-Tacy books by Maud Hart Lovelace
The Egg and I by Betty MacDonald
Voyage of the Dawn Treader by C.S. Lewis (any of the Narnia books really, but DoT is the best for comfort because you get the most Reepicheep per page.)
Lizard Music by Daniel Pinkwater
and anything by Dorothy Sayers.
eleanorigby, my favorite Tey books for comfort reads are Brat Farrar and The Daughter of Time.
When I’m in a waiting room or something. I like to read something I have read many times, short stories like The Good Old Stuff and More Good Old Stuff by John D. McDonald, or any of his Travis McGee novels; any of Stephen King’s early stuff;** Rex Stout**'s* Nero Wolfe* series, especially* Some Buried Caesar* or In the Best Families, or anything where Wolfe leaves his familiar 35th St. environs and Archie has to lead him around in unfamiliar circumstances, all while cracking wise and getting under the skin of the local constabulary. Great stuff.
** Ed McBain*** 87th Precinct* series, especially the ones concerning the Deaf Man.
- Catch-22* by** Joseph Heller**
The Hotel New Hampshire, The World According to Garp, A Prayer for Owen Meany * by* John Irving**
On a Pale Horse by Piers Anthony or any from that series is good for a quick read. - It’s a Small World* by Tabitha King (** Stephen King**‘s ol’ lady). Creepy.
“Most Reepicheep per page”! That’s brilliant!
I notice no one reads Ulysses or Nietzsche for comfort.
This is fascinating, so I’m bumping it.
God, I thought I was the only person who ever read (or re-read) that one. It must be 10 years since I read it last…too long, I think.
I just recite Nietzsche by rote in a trance while listening to Wagner. How’s that? 
My comfort books lately have been Tam Lin by Pamela Dean, The Interior Life by Katherine Blake, and Once a Hero by Michael Stackpole. I have quite a few others (such as the Eddings books and almost anything by Elizabeth Peters), but they’re (still) packed.
I really need to move boxes and put up bookshelves and mind the bar code scanner and shelve my books while scanning them into Readerware. Gonna take a while, though. sigh
I’m reading Kerry Greenwood’s Phryne Fisher Mysteries.
Its a great read. I’m from Melbourne and it is interesting to read about what it was like in the 1920s, but the heroine is comfortingly modern (perhaps a female Indiana Jones combined with a young Mrs Marple!)
I recommend it (also helps to support Australian authors)!
All seven of the Anne of Green Gables novels except for the last one. Rilla of Ingleside is set during WWI. I find it too painful to serve as casual entertainment.
Oh wow, I also love Tam Lin as a good comfort read! I also like to read it in the fall, it’s such a great back to school/halloween book.