The Harry Potter series made clear that grown ups can be swept up by imagination if it is high quality storytelling.  Pullman's Dark Materials series come to mind as another fantasy that is of high quality and suspense.  When I was a teacher, read aloud was my favorite time of day because I could read kid's lit.  Some of my personal favorites are by Kate Camillo.   The Journey of Edward Tulane has some of the most amazing symbolism, it gives me chills to read it.  I grew up on Anne of Green Gables books and still like to turn back to those stories when I want the comfort of returning to old friends.

What are some other favorites of PBS readers?

I loved the story "Because of Winn Dixie"  It was very well written - I think kids and adults alike would enjoy it.

I was raised on Robert Heinlein's "Books for Boys" and they remain some of my favorites to this day. 

I have not read any (yet) but based on how much discussion they get here, I think Stephenie Meyer's Twilight series must have plenty of adult (well, legally speaking :p) readers.

I read the Twilight series and I loved it!!!  And I'm not a kid.  Well at least not age wise.:0)

I've enjoyed the YA books of Cornelia Funke, Susan Cooper, and Neil Gaiman.

Anne of Green Gables and all the others that follow.

My daughter and I both enjoyed reading the Mediator series by Meg Cabot together....

Two absolute favorites:

The Underneath by Kathi Appelt. This really, really, really needs to / should win the Newbery this year.

The Miraculous Journey of Edward Tulane

I enjoy Shel Silverst, especially THE GIVING TREE and Dr, Seuss, especially OH, THE PLACES YOU'LL GO!  These may be considered children's books but the message in both is for all ages.

I still love Roald Dahl, the Mrs. Piggle-wiggle books, the Narnia books, the boxcar children, Frances Hodgson Burnett, Lewis Carroll, Black Beauty, Nancy Drew, Catherine Called Birdy, Tom Sawyer, Bud Not Buddy and a ton of others.

Mrs. Piggle-Wiglgle books, who wouldn't love them.  I know I still do and I can't wait to have children to read them to.

i enjoyed the Heartland and Chestnut Hill series by Lauren Brooke

i also enjoyed

teen witches,oh man there is so many im always reading teen books

Roll of Thunder, Hear my Cry is an excellent book

Thinking about it, I believe most of Medeleine L'Engle's books are considered YA.  A Wrinkle in Time and the related books are still good.

I enjoyed The Island series by Korman and the Among the Hidden series by Haddix.  And of course the Little House series.

Glad I'm not the only, um, adult who still reads the Boxcar Children books! :-') I love that series, even the newer ones are good!

I also love A Tree Grows in Brooklyn(not sure this is YA but I think it is), The Secret Garden is awesome!, and as an adult I discovered the audios of A Year Down Yonder by Richard Peck(my favorite with the female narrator) and A LOng WAy from Chicago by Peck is also good but a male narrator on that one and has different stories jumbled together.

I was gonna post the same thing as Barbara. The Mediator series by Meg Cabot. I haven't read any of her other stuff yet but I plan to. I really like her writing.

A Long Way From Chicago by Richard Peck... I just read this a loved it so much that I ordered the sequel  - A Year Down Yonder.

I am enjoying the Twilight series as well!    I also still love the Narnia books. 

Jessie the audios of those are great too!

I recently discovered The Edge Chronicles by Paul Stewart and Chris Riddell.  I found book one when I was looking for a book for my granddaughter.  I have read the first three books and have really enjoyed them.  The next four are in my TBR pile and I will more then likely get to them in the next week or so...They are really good books and keep you on the edge of your seat most of the time...Can hardly wait to see what Twig will get into next.

One I haven't seen mentioned...."Nick of Time" by Ted Bell

Megan Whalen Turner's Thief series is excellent.  For Harry Potter fans, Diana Wynne Jone's Chrestomanci series is very enjoyable.  I would start with The Lives of Christopher Chant.

The President's Daughter series is really good. There are four of them with the likelyhood of another one being published in the future.The author is Ellen Emerson White.