I like comprehensive documentaries, particularly when a film really deserves it or has an interesting production history. In other cases (the original Alien vs. Predator) the documentary can sometimes instill me with a newfound appreciation for the film.
In AVP's case, Anderson's giddy fanboy excitement to be doing this film was palpable in the documentary, and it definitely made me a fan of his, even if the film itself sort of wallows in mediocrity.
Meanwhile, there are Scott Free DVD's from Charles De Lauzirika, and there's everything else. The Alien quadrilogy, the three disc versions of Gladiator and Black Hawk Down, the Kingdom of Heaven director's cut, and the king, Blade Runner: The final cut.
These discs contain some AMAZING, all encompassing documentaries that are feature length experiences in and of themselves, and rival the very best film-based documentaries in existence.
As the ancient Tibetan philosophy states:"Don't start none... won't be none...".