I haven't done research on Ambrose himself but I have read a few of his books and find I can never put them done. If his assistants were the major force behind it then they should continue the legacy.
I think for me the book research would be such an unbelievable experience that I would feel like the book would never be good enough! The thought of getting paid to travel around the world to sit down with soldiers, politicians, civil rights people, the ones that were there and lived it, would be the greatest job in the world. I can't even imagine the emotion in these interviews. How can you put it on paper and do it justice?