Ian,
I would expect the Gil Hanse course and the other one mentioned by Jeff would be easy walking courses as that area is generally flat or gently rolling country. The coastline along the east side of Vancouver Island is definitely conducive to walking courses.
Otherwise there are plenty of courses built in the mountains but a lot of those are very easy walks. If you consider the three courses at Whistler, the original Palmer Course (Whistler Golf Club) is quite flat and in the valley bottom with the exception of a couple of holes on the back nine. Nicklaus North is very flat and ends up winding along the edge of Green Lake. The Chateau course (RTJII) is VERY hilly and a very difficult walk. Down the road in Pemberton, Big Sky is surrounded by huge mountains but it quite flat and an easy walk.
In Vancouver, all of the courses (save perhaps Northlands in North Vancouver ) are easy walks as well. There is a huge difference in the various areas of the province which of course, is huge.
Regarding the interior, I am not as familiar with those in the Kootenays as I am with those in the Okanagan but you are likely correct. Sagebrush is being promoted as a walking course, Kelowna Golf Club, Harvest Golf Club, those in Osoyoos and maybe more are definitly walking. It just depends on location just like anywhere else.
Finally, Capilano is definitely hilly but remarkably not a difficult walk. Thompson, as I think was pointed out by Ran in the course review, certainly designed Capilano such that the elevation changes are traversed in a gentle manner, for lack of a better term.
Regards,