Oooh, I'm sure you guys will regret staying only one week north of the border. You will love Vancouver and the surrounding areas. There are tons of things to do around here, especially for kids. I suggest you do your homework before arriving and decide which ones you want to see. As a place to start I suggest
www.littletots.ca or
www.findfamilyfun.ca. They have lots of kids attractions and activities for the Vancouver area.
Also try the vancouver parks board website:
http://vancouver.ca/parks/
Have fun!!