I think it also depends on the service that is run to your house...
If my memory serves me correct I think that my brother had 200A service run to his house because he wants to be able to run a Welder and all sorts of power tools in his garage.
I checked with an electrician here at work and he said that 200A service is Standard now for all new construcion in BC. If your service is 200A then you could possibly replace your panel with a 200A panel and then run your sub panel from there.
(I could be totaly out to lunch on this)
Joel