Depending on where you live, how long you're travelling for, and how much you value your time, a taxi may be a better option. Generally, more than 3 days would make taxi a better option for those residing in Vancouver proper (less if you live closer to the airport).

There doesn't seem to be too many options other than the yvr.ca lots and the Park 'n Fly. The Days Inn/Hampton Inn complex on Bridgeport Road seem to have some fencer-off parking facilities.