Howdy BicycleBoy -
You give only a few outlines, but here's my take:
(I've toured for twenty years -
six cross-USA trips and tens of thousands of miles in the West.)
The Western Express is really not a good starter tour route - esp. solo.
In addition, starting eastbound after mid-June can put you into some really hot weather.
The challenges are both physical and mental.
Within two days you have major climbing to do to get over Carson Pass - 8800 ft.
Nevada and Utah are really, really tough.
Not only do you lack services for 70, 80, 90 miles -
but you have three of four passes to climb every day.
Then there is the mental strain of the miles of starkness.
I remember my early cross-country rides - esp the first.
I was glad to have the little towns every 20 miles -
With a cafe/store and a little grassy spot and a tree.
It allowed for more stops - chatting with people -
Not worrying about exactly where to get to.
The TransAm route across Oregon is one of the best possible W to E routes
You don't have the urban traffic of San Fran or Sacramento.
You get Eugene two or three days into the trip where you can get
last minute tweaks at bike shops and any additional touring stuff you forgot.
There a greater chance you will bump into someone to ride with - if you wish.
The climb over the Cascades is gradual - alongside rivers and streams.
On the east side you wind thru John Day country with frequent small towns.
If you feel pinched for time you can cut thru central Idaho and avoid Missoula.
The Idaho Sawtooths are stunningly beautiful - a great ride to Yellowstone.
But you would miss the Lochsa River and the Big Hole Valley - two fine sections of the TransAm.
And if you are going to Iowa you can cut off the TransAm around Lander, Wyo.
Then cross Nebraska along routes of the historic western trails.
I don't know your age or experience level.
But you said it would be your first tour.
I REALLY think you would enjoy the TransAm option more.
Then you can look forward to the Western Express for your next tour.
Just my 5 cents.
Best - Jama
My crazyguy journals on Nevada -
http://www.crazyguyonabike.com/doc/p..._id=40749&v=1R
http://www.crazyguyonabike.com/doc/p..._id=26321&v=Qs