Wow, Chris what a spectacular rock garden that is going to be. I love it already. Any of the semps and hardy sedum will do well in there, and will colonize quickly. Maybe the tinier types in the upper levels, larger more to the bottom? Mixing colors and textures throughout for eye appeal?
It looks like you might have a few tender type succulents in the photo above, they won't make it through winter. But you could arrange niches to set the pots down into the rocks, would be easy to lift them and take indoors for winter.
You have a great place in Canada to get new semps from
http://www.drought-smart-plant...
She has an amazing assortment of wonderful semps and other types of succulents.
Your Blue Boy is wonderful, one of my favorites.
