What kind of fuel economy do you get in the Suburban? If you get close to the mid 20's mpg you are better off fuel use to take one Suburban than you are taking two economy cars.So the volt beats the Prius on this trip and blows away the Prius on a normal city commute. So why are people still buying priuses (prii?). Alas for a trip like yours, instead of taking 2 economy cars, I would have taken my Suburban. Screw fuel economy, I'm going for comfort and space for the kids and cargo - one driver vs. two - family bonding time in the vehicle.
Keith