Google maps gets better and better. In fact, their latest added feature completes its feature set and makes me perfectly happy. What now, you ask?
Well, after including exit numbers not too long ago, now you can freely change your route by dragging the blue line of the computed route. If you do not like the itinerary Google computed, e.g., sending you over the George Washington Bridge, rather than the much better route via the Tappan Zee Bridge, you can simply point your mouse to the blue line (it will show a square) and then click-and-drag to where you would rather go.
The new point gets incorporated as a stop and the route is recalculated instantaneously. Wonderful!