We used the Skytrain (subway) from Canada Place to YVR, the Vancouver airport. The cost was 3.75$ (Canadian), and it took about 30 minutes. It is an easy walk, and a great way to save at least 25$ each. (For some reason I do not know there is a 5$ surcharge from YVR to Canada Place, but not in the other direction.)
It is an easy 5-10 minute walk to the Skytrain station from Canada place, even dragging 3 roller bags. There is plenty of room for bags on the subway. It discharges you right near the international terminal at the airport.
999 Canada Place
Vancouver, BC V6C 3E1, Canada
1. Head northwest on Canada Pl toward Burrard St 400 m
2. Continue onto Thurlow St 210 m
3. Turn left onto W Pender St. Destination will be on the right 90 m
1050 West Pender Street
Vancouver, BC V6E 4T3, Canada
If you want to take a cab there are a lot to choose from at the terminal. Be careful about using a porter at the terminal, because they are not allowed to take the rental luggage carts out of the terminal.
Just reverse if you are coming from YVR to Canada Place. The Skytrain has specific stops for both YVR and Canada Place.
Hope this helps.