@dlowan,
There are quite a few books I reread when I am in a dry period, meaning trying to spend less on books, and there are a few that I turn to regularly and read on an annual basis. Some tend toward the highbrow end, some are just brain candy, but most settle somewhere around the middle:
The last three books of the Harry Potter series
Earthly Powers by Anthony Burgess
the Songlines by Bruce Chatwin
Rituals by Cees Nooteboom (trans. by Adrienne Dixon)
The Glass Bead Game by Hermann Hesse (trans. by Richard and Clara Winston)
The Illuminatus! Trilogy by Robert Shea and Robert Anton Wilson
The Pound Era by Hugh Kenner
The Dialectics of Seeing by Susan Buck-Morss (about Walter Benjamin whose essays I reread often too.)
The Geography of the Imagination by Guy Davenport
A few different Penelope Fitzgerald books, particularly her group biography:
The Knox Brothers (Just thinking about this one is making me want to go pick it up right now for some reason.)
Cats Cradle by Kurt Vonnegut
The Nicholson Baker oeuvre in general
The Thought Gang by Tibor Fischer
Fathers and Sons by Ivan Turgenev (my current copy is trans. by Constance Garnett, but I had another whose translation I preferred. I can't remember who did it or why on earth I got rid of it.)
The Anxiety of Influence by Harold Bloom (which I loathe, but I keep rereading it to refresh my dislike.)
There are probably a couple of others that I've forgotten, and I've missed them during my scan of the bookshelves. Also, a few years ago, I made a project of rereading all of the old paperbacks that I still had from when I was a kid/teenager. I've been hauling them around for years and I decided to get some use out of them, see if any of them held up. Most didn't and weren't actually finished, but I enjoyed a few of them so much that I've reread them several times since the beginning of the project.
The Dark is Rising series by Susan Cooper
The Ender series by Orson Scott Card
My Side of the Mountain by Jean Craighead George (which I would recommend to any parent for their children.)