On a Bryson-esque travel note I would recommend Tim Cahill. Slightly more extreme travel than Bryson - Eg. "Tim Cahill has clambered up Mount Roraima in the Guyana highlands, searching for the site of Arthur Conan Doyle's Lost World. He's dined on baked turtle lung in the desolate northeast of Australia and harvested poisonous sea snakes in the Philippines"

Humorous and, for me, a page turner.

I would also recommend Terry Pratchett. Not sure if he's well known in the States but here in the UK he is huge. (Some stats suggest his books account for 6.5% of all hardback sales in the UK, and 2% of all book sales). The books are not exactly intellectual, but are thought provoking (although we're not talking Dostoyevski here). The books are very funny, and imaginative. Would suggest starting with 'The Colour of Magic' and 'The Light Fantastic'.

Other faves :
Jack Finney - Time and Again. Thought provoking but not difficult.
Alfred Bester - The Stars my destination. Classic SF with more pace than most of today's efforts.

Wow! Ask for a book recommodation around here and look what happens.
I too love the Harry Potter series.
Larry McMurtry's Deadmans Walk is a surprisingly engaging book. We listened to it as a book on tape on our last trip to New Mexico. Also Commanche Moon was very good.
Bill Bryson is always delightful. I like Sunburned Country.
I just finished wonderful book called,
Bel Canto. It was a superb read.
Also I don't think you can go wrong with a mystery on a plane. Sue Grafton,
Tony Hillerman.
Bernard Cornwell's The Archer's Tale was a real page turner.
And I love that someone suggested P.G. Woodhouse, always good for a laugh and very much a no brainer.

Lanchester's "The Debt to Pleasure." Sue Monk Kidd's "The Bea Season." Anita Diamont's "The Red Tent." "The Last Kashmiri Rose," a mystery by a very talented new writer, Barbara Cleverly. And of course John Le Carré's "Tinker, Tailor, Soldier, Spy.