Is there a way to get a plot of the total vertical feet ascended on
various bike routes across the US?   Obviously anyone who has done it
with an integrating altimeter has the information, so would the
information have been collected for the 9-10 routes most commonly
used.  Possibly there is
a GIS solution.   I would like to compare difficulty of bike routes
this way.  Am 67 and looking to do this trip, let's say San Francisco
to Boston, the easiest way possible.

You could purchase Topo! software
  http://www.nationalgeographic.com/topo/
and do plots of your proposed routes. Once the route is plotted, tell
the software to "Build Profile", and there's all your information. If
you don't need huge amounts of detail, like elevation changes of less
than 100 feet, you can do what you need to do with the Topo! CD pack
for a single state like California; low-detail maps of the entire US
are included.

I just did San Francisco to Salt Lake City via I-80 as a test, without
much effort to keep my cursor exactly on the road, and got this:
702.50 miles, total gains 40,016 feet, total losses 35,868 feet, net
gain 4148 feet (the difference in elevation between the two cities).