I agree with valygirl that you can consider other "cross country" routes. You also have the Great River route in central but have only done a portion of it.
Another option is to consider a multi-country route, i.e. Pueblo, CO (or Jackson, WY to save time) to Jasper, AB but you would want to plan on rest days every 5-7 days due to the wonderful national parks you would be visiting.
You are smart buying a used high-end touring bike. I use a 17 year-old Bruce Gordon that is probably better than most new bikes. Be sure you have strong wheels, good racks, buy used decent packs (Beckman or Arkel), and tent/sleeping bag. You can put the money into other areas instead of a new bike.
Be sure to plan a few days back home before you return to work to readjust to "life". Numerous funny stories of how we have to readjust, i.e. not thinking about taking TP with you in case there is any.
Have a wonderful trip!
Happy trails and may the wind be at your back!