The first time I watched it was in chronological order with deleted scenes. And then when I bought them on video I was disappointed to find that Part II was not in chronological order (I had assumed that Part I had De Niro in it). But now I prefer to watch them separately, (I haven't seen it chronoligcally since the first viewing) as I feel that the Cuban sequences lose their interest without the anticipation of wanting to go back to the Young Vito scenes.
Oh, and Pherdy, you know I love you idea of a Memento style viewing of the Godfather! Do you mean the films themselves, or watching them backwards scene by scene too? That would be even better!
Mick