An east-to-west traverse would be the only way to trek this without disappointment, wherein the reward for surviving the un-fun and mostly flat east and lower Great Lakes, upper Appalachia excepted, and the windblown monotony of the Great Plains is the Rockies and the Pacific Northwest/Cascades, which are beyond awesome.
Do it west-to-east and you've seen everything worth seeing by Wyoming, so utterly underwhelming is everything east thereof.
I once started in Washington, D.C. and only made it to Chicago before giving up from overwhelming boredom, jumping the Amtrak (train) to Denver before continuing west.