Since you mention Maui, I'll give you my two cents.
My feeling is that kite size choice is specific to many variables, including, but not limited to: local riding conditions, rider experience, rider size, personal preference, and the list goes on.
My best guess from what you've written, but without knowing Vancouver (other than its a super rad city, and my first stop on the way to Whistler!!!) is that your thinking for a 7 and 9 to add at some point to your 11 sounds awesome. I think you'll want to take local advice specific to your riding areas (and not mine from Maui). Maybe look up Kyle Touhey on Facebook.
For Maui, I could do 95% of my riding on a 7m (assuming it is a kite with good range). My wife does most of her riding on a 6m, and there are plenty of days when she's too lit, so we just got a 5m. So, a 6, 8, 11 quiver may be more Maui-friendly for a 3 kite quiver. Or, up-ing it to a 4 kite quiver of 5, 7, 9, 11 may be even more Maui friendly. Still, in Vancouver, it may be you'll get way more sessions on a kite bigger than 11, instead of adding a 5m. So, it gets confusing, and leads me back to the importance of local advice (so ignore my comments outside of those for Maui).
If I may add to your post: I'm very interested to hear what everyone's dream quiver is for where they ride. Not brands/models, but just number of kites in the quiver, and what sizes, specifying the riding location(s). For example, mine is:
Maui1 kite quiver: 7m.
2 kite quiver: 6, 8.
3 kite quiver: 5, 7, 9.
If I'm going to travel, add a 13m.