Okay, so I know this sounds bad, but it's true(in my opinion): I always judge books by their covers. Always. If the cover doesn't appeal to me, I probably won't read it! I don't know if it's just the designer in me that cries out for creative cover concepts, or whether I am just being picky.
Also, thanks to everyone's great recommendations on books! I am taking them all into consideration next time I am standing in front of the Penguin Classics shelf :)