I've been on a massive graphic novel kick this year. Thus far I've read IDW's entire Ghostbusters run, Gotham by Gaslight, Thor (the one where he brings Asgard back from the dead), and the Green Lantern/Green Arrow Denny O'Neil run from the early 1970s which is a masterpiece.
Currently I'm on the hunt for the entire John Byrne 1980s Superman run. This is where Byrne completely reboots the character and does some absolutely revolutionary things with the character. One of the most significant changes Byrne does is make Clark Kent is the "real" person and Superman is the disguise.
I've read some reviews online that states this the definitive run on Superman. I for one cannot wait to read the entire run. There is a total of 8 volumes, I currently have 3 purchased.