I've read The Wheel of Time series by Robert Jordan many times. Usually everytime a new book in the series came out, i'd re-read the entire thing. There are 15 total books (counting the prologue), so that amounted to quite a few re-reads!
I've also read The Fountainhead & Atlas Shrugged many, many times. The Fountainhead is my favorite book of all time. I like to re-read them both from time to time to see how age has shaped my view of the philosophy.
The other books I've re-read in the last few years were all books I first read at a young age and I wanted to re-examine. To Kill A Mockingbird was one, and I found it only gained more depth and meaning for me as I've aged. Another was The Pearl by John Steinbeck -- I first read that in 8th grade and HATED it. I was reflecting a few months ago and realized it is the only Steinbeck novel I've ever hated, and thought perhaps I was just too young or willful at the time to appreciate it so I gave it a re-read, and sure enough, I have a fresh appreciation for the book. Which made me want to re-read some more Steinbeck.