I recently purchased a GPS and I would highly recommend one for anyone driving for business. I will never go back to using printed route instructions. The GPS is like having a navigator in the seat next to you.
And they are cheap now--I paid around US$200 for mine. A business could easily save this amount by the drivers not getting lost anymore. Mine will even automatically reroute you around highway traffic jams (in certain large cities only).
Another issue is that when using printed directions and you make a wrong turn or miss a turn, then you are on your own. With a GPS, it automatically recalculates a new route and then tells you where your next turn is. Awesome!
James