I just rode the Golden Trangle: Radium-Golden-Lake Louise-Radium. It was a fantastic ride, but now it is time to start planning for net year. We would like to incorporate Highwood Pass or Kooteney Pass into a 300-400km loop. Does anyone have any suggestions? Anywhere with mountains in BC, AB, WA or MT.

You can make some decent loops starting out of Cranbrook. Check out this guys site

Incorporating the Highwood into a nice loop is a bit harder, although an out and back on Hwy 40 is pretty good.

For a bit longer trip:
Pincher Creek - Crowsnest Pass - Fernie - Whitefish - Logan Pass - Pincher Creek 500km

Alberta Randonneurs have a 300 km Highwood Pass route starting/ending in Cochrane:
https://www.albertarandonneurs.com/ma...assic-300.html

That looks epic.

I'm planning to attempt a variation on that ride in early July. I doubt it is suited to the OPs interests though as it is mostly foothills/prairie terrain with just the one pass.

Interested but it's a lot of driving for one pass particularly for my west coast riding partners. Its a conundrum. These darn mountains seem to be natural obstacles to building roads to ride on.