Have contacted the bicycle coordinators with less than great success. The particular states of interest do not publish bicycling maps with recommended routes (I think for legal reasons). Some have maps showing shoulder width but it is not combined with traffic volume and in some cases does not have the route identified with the lines so much is left to the user. I found the standard state issued highway maps to be the most worthwhile resource for both Idaho and Utah.
I am (also) very disappointed that the I-84 corridor with the Columbia and Snake rivers and major cycling cities is not on the US Bike Route System planning map as I think it makes a lot of sense.
I am sorry to hear that you didn't find what you were looking for from the bicycle coordinators. Sometimes you can find better information by going down a level from the state and look at county-based resources. What states or specific areas are you looking for information on? Maybe I can point you to some resources. In the meantime, I have added some links to items that may be of use to you in your planning.
I found a traffic count map for Idaho you might find helpful:http://itd.idaho.gov/planning/roadwaydata/
Utah has both a suitability map showing shoulder widths:http://www.udot.utah.gov/main/f?p=100:pg:0::::V,T:,275
and a traffic count map:http://www.udot.utah.gov/main/f?p=100:pg:0::::V,T:,528
Nevada is usually pretty responsive to requests, have you seen what's available in their Bicycle Travel section? If those aren't what you are looking for, try contacting them directly.http://www.bicyclenevada.com/
I hope at least some of this helps.