The FBI timeline included details of some flights booked by (or for) the hijackers, after 9/11. I thought the FBI case file referenced might contain some useful information, so applied for it via FOIA and it's just arrived. It doesn't actually provide any answers, and there's a reference to one of the flights being booked after 9/11 which will please the "hijackers still alive" people, but here's the file anyway for those who are interested.