We've done this before, and although we were able to mostly make it through Stephen King's gigantic Under the Dome, shorter is better in these kinds of things. As much as I want to participate, I've got a lot of junk coming up in the near future and I've gotta spend most of my reading time doing "work" reading for school and suchly. As much as ruling out longer books seems like a bad thing because you'll be getting rid of classics, just imagine how many great shorter works there are. Looking at my top 50 list, almost all of the books I love are either short or long but "easy" reads, including comic books and the like. Basically, read the long stuff on your own time, it'll just gunk up the works of something as hard to organize and keep up as this.
But, that's just, like, my opinion, man.