Hi, and thank you both. I did post on all the relevant State's forums, I hope that's not overkill!
We'll be travelling late August, early Sept.
If we were to take the Missoula/Walla Walla route, we'd do it over 2 nights, stopping either directly in those places or nearby. It doesn't really matter where we stay on the journey as long as it approximately breaks up the journey.
I think we'll spend 1 night at St Mary on the East side of GNP. We'll head out after an early start and spend the full day exploring the GNP area, and eventually working our way down to Missoula. We'd overnight there or nearby, then spend the day driving on to Walla.
Travelling via Spokane seems a bit shorter. Taking this option it might be better for us to stay on the other side of GNP. I think we'd spend one night at Coeur and then push on to Portland. If we did that we'd free up an extra night for Seattle or Portland and still be able to do the trip in 14 nights.
Vancouver 3 nights
Revelstoke 1 night
Banff 2 nights
Calgary 2 nights
Glacier 1 night (St Mary Lodge, Cabins and Motel)
Missoula 1 night
Walla Walla 1 night
(Or Coeur, 1 night)
Portland 2 nights
Seattle 3 nights
We're basically happy to spend full days driving, taking the most scenic routes. We're not hikers or anything, so just appreciate being able to stop the car, gawp at the big American landscapes and take photographs, and may be take short walks to vantage points and scenic spots. Wildlife spotting would be a nice bonus. A bit of culture and history would also be nice to squeeze in. A nice town to spend lunch in would be good too. We've both visited vinyards in Europe before so that's not too important.
We did a similarly massive trip last summer, a grand circle from LA, going as far out as Monument Valley, Yosemite, and SF. In many of the places we didn't have long to stay e.g. 1 night in Yosemite. It's more about seeing as much as possible. We'd love to do these trips over 3 weeks but work and budget don't allow, I'm afraid!
So I guess it comes down to whether the journey from GNP to Portland is worth investing 2 nights in, or whether it's better to plough on to Portland and take only 1 night en route. I've read about two great drives near Portland (Mount Hood/Columbia River) and I want to ensure we have time for those.
Feedback much welcome to help me refine the route.
Route 12 does still seem to be coming off the best. Carcar's point about the traffic was a good one - we don't want to be stuck on busy roads, we get enough of that in the UK, we want all those lovely long empty roads!