It can be hard to hail a cab in Vancouver. Unless you're near a hotel or find a taxi rank (designated curbside parking areas), you'll have better luck calling a taxi service. Try Black Top & Checker Cabs or Yellow Cab. Both companies allow you to book online.
Black Top & Checker Cabs (604/731–1111. www.btccabs.ca.)
Yellow Cab (604/681–1111. www.yellowcabonline.com.)