I think decent shoes you can walk a long way in are a must - only time I had a problem recently was of course the time I'd rotated my hikers for a pair of gym shoes :-(

For me at 35 miles from home, walking back is the extreme solution, though walking part of it isn't a bad idea.

One suggestion (preaching to the converted here I suspect) is to think about what you have on you - if the building gets evacuated and you are in the cafeteria / meeting room / someone elses office then you won't be able to go to your desk - leaving car keys and phones in a desk draw (as some of my colleagues did during a recent fire drill) creates a drama out of a crisis