I checked a variety of car rental companies, as I'm sure you already have, for a minivan
rental one way from Vancouver airport (YVR) to the Phoenix Airport (PHX) ---no go!
I then tried a few companies for separate minivan one way rentals - YVR to Seattle, Washington (SEA) and then a second one way rental from SEA to PHX.
This is doable (car rental company links open in new windows).
With Avis or Budget, the only vehicle availability would be:Avis -- compact, mid or fullsize car for YVR - SEA then SEA to PHX
With Hertz you can get a 7 passenger Chevy uplander or similar , one way from YVR to SEA -- I assumed a one day rental (pick up & return within 24 hours) from Vancouver to Seattle and a two day rental (pickup & return within 48 hours) from Seattle to Phoenix.
When you check rates, make sure to use any discount information that you may have to try and lower the price.
Hope this helps!
Pages from this site, relating to this topic:
One Way Car Rentals