Re: Here's some ideas
Helicopters landing on the roof doesn't seem practical since the smoke causes visibility problems, and aircraft arrive too late to do much good. So the escape route needs to be part of the building itself.
Parachutes is also a bad idea since no one is going to be able to use them safely in such a confined space. People sliding down guy-wires might be better, although a lot of people might be scared of heights.
What about lifeboats? Just like big cruise ships, and oil rigs. Lifeboats on guy wires? Each life boat carries 100 people, and rides a guy wire to safety.