If I'm touring alone my plan is to fly to Great Falls, Montana and ride the Lewis and Clark Trail to Portland, Oregon, then take Amtrak home. (I'm even planning on splurging for a sleeper car!)
If I have any luck getting someone to go with me I may do the Oregon coast again, or even start in Vancouver, BC, and ride the coast down to Crescent City, or even San Francisco. I have a couple of potential first-time tourers who may want to go, and I think the Oregon coast is pretty good for a first tour - lots of campsites, lots of fellow tourers to meet, plenty of services, etc. If you get good weather it's hard to beat, at least in the US.
If I go alone I want to go somewhere I've never been. I'd like to do the whole Lewis and Clark trail someday because it intrigues me and I'm a Lewis and Clark buff. But I won't have time for all of it. (I need to retire one of these days.
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