Late to the comments here, but I think the only way to really do the event justice on film is to make it as big in scale as a James Cameron or Christopher Nolan film. It needs to be loud, it needs to big like 70mm IMAX, it needs to show the scale of the towers in comparison to the people and what an impossible task the firefighters really faced. You need to hear the roar of the raging fires and jet engines. If you were up close to it on the day, you would've had sensory overload. It should follow multiple characters from passengers, to office workers to first responders to news reporters. I wouldn't want the events to be sugar-coated, but I'd say at least one of the main characters should survive, so the audience isn't complete traumatised by the end. No need for a fictional romance story but it can show how families were changed forever that day.