Without knowing your time constraints, I would suggest taking US Route 50
West of DC all the way to Pueblo CO and then working your way over to RT 160
and Wolf's Creek Pass and then on through the Four Corners area to the Grand
Canyon. The path on out to your CA destination would be determined by time
remaining.
This route would allow you the more scenic parts of the East...the
Appalachians are training grounds for the Rockies, a pretty ride through the
better parts of the rolling hills of the Ohio and Mississipppi River Valleys
and on to the Great Plains; arriving at the Rockies with out trying to keep
up with the interstate traffic, you can still feel like you aren't
completely numb after all the corn and wheat fields.
The desert SouthWest is a whole 'nother world of travel, full of lots to see
and ponder; but as a midWesterner, I would recommend at the least the Grand
Canyon if you've never seen it before.  Be sure to travel the South Rim away
from the main tourist areas in order to get some spectacular views and
perspectives.
It's a great country and with this route you would get to see a lot of it
and even get to meet some of its citizens where they live and work.
Just my $.02 worth. Have fun and enjoy your trip.
Stephen
Chillicothe OH