The National Geographic doc is definaltly the place to get all the information about Air Force One and how it operates.
One thing quite different to commercial operations as stated I think by the previous commander under George W is that diverting is not an option, so if the weather looks dubious they are still going in! I imagine that if it looks very bad before they left they might change plans somehow but if it changes while en route at some places they would have to land there anyway!!