Well, I'm not into first printings except for particular favorites, like this one. In general, it's the cover design and such that attracts me. Although, if it's not an author or book I enjoy for the content, it's hard to justify adding a book to the shelves. What I have is more of an accumulation than a collection, really.
I've collected comic books, coins, stamps, and vintage paperbacks in the past; I'm kind of between obsessions at the moment. This has mixed results; I feel like something is missing, but on the other hand, I'm not broke all the time...