When I speak to people about directions, they usually refer to Google Maps. However, I have been burned twice by Google Maps giving me the wrong directions. For example, yesterday, I was going to 165 University Ave, Toronto, ON, Canada and I entered this in maps.google.com and was giving the wrong information and ended up almost being late for my interview. The previous time I was late for a funeral when I ended up miles away from my destination.
Yahoo! Maps has the correct information (as it did the last time). At a minimum I recommend you check both of them, especially if you have an important appointment. Or just use Yahoo! Maps.
Smart People I Know 