A lot of Neal Stephenson's work holds up to rereadings. I've gone through the Baroque Cycle + Cryptonomicon maybe three times now, and I guess I'm due for a fourth soon.
Cryptonomicon I am at about 15 reads (including audio book listens a few more), and maybe a handful for Snow Crash, Anathem and Reamde.
My book of choice for re-reading is Not a Penny More, Not a Penny Less, by Jeffrey Archer. I must be at 50 re-reads of that now, and I own two first editions. Strange what catches your mind!