Nav has some a LONG ways in the last decade. Even ignoring all the fun stuff, cool apps, social networking, etc. Just plain nav.
Current nav systems, like the default Google/Android nav manage to:
* Adaptive routing based on traffic conditions and accidents
* showing now only which direction...
Having done quite a bit of driving in snow/ice in some very adverse conditions I figured I'd mention a few things I haven't heard on this thread yet.
First I'd consider how flexible can you be. Can you take public transit, carpool, or related? Will you be fired if you can't make it to work...