No music stores in the mall...which is kinda weird. You'd think the largest mall in North America would have at least one place to buy a crappy guitar...
http://www.westedmontonmall.com/home/default.asp
As far as music stores in the city, I know there is a Long & McQuade, Axe Music, and a Mother's Music...all of which are pretty average, but if you have nothing better to do/need strings or something, they aren't bad. Pretty much just GC North.
Google maps is your friend.