Website showing elevations and grades?

"From what I've seen on the Mountain Directory sample, most of its information is the kind of thing you will see in the road signs at the top of various passes and grades"....

Correct, the only difference between the book and the hiway signs is that you can see what you are going to encounter long before you commit to the chosen route.

The books are invaluable in providing the information ahead of time to keep you out of trouble.... IMO

Regards
Gemstone

From what I've seen on the Mountain Directory sample, most of its information is the kind of thing you will see in the road signs at the top of various passes and grades. The kinds that warns trucks of 6% grade ahead.

When I am planning a unfamiliar route, I consult this:

Mountain Directory

ebook version is available.

fred

Google maps suggests routes between places, and lets you modify them. With terrain mode on, it shows topography, including contour lines when zoom in enough. Grade though has to be calculated by asking for the 'route' between two contour lines, and dividing the elevation difference by the distance.

For example on this map
Washington Pass, WA20
the road climbs 1000 ft in 3.3 miles

grade is 1000ft/(3.3 miles * 5280 ft/mile) = 5.7% grade

Most western state DOT web sites list major passes and have pass elevations. Some also give the maximum grade.