I choose my locations based on distance for a day. Recently I rode 600 miles from central NJ to 150 miles north of Montreal. I picked each days end (about 75 miles) and found a reasonable place to stay. Then I clicked on get directions (for bike) between each stop. I then went through the directions one step at a time and clicking on the yellow person icon to see a photo of each turn (where available). The interface walks you through each leg of the directions very nicely. I make adjustments to the route as I see roads that are not suitable. Then I print out the turn by turn directions and use them (in a plastic map case on my front bag) as I ride.
I've done this a few times and it has served me well. It's a great starting point and can easily be modified.