I drove Dodge minivans as work vehicles for several years, and cannot recommend anyone buy a Dodge/Chrysler minivan. They are cheap, and that is about all they have going for them. My folks even had one start on fire from a wiring harness issue in the rear of the van. As work vehicles, we dumped them at 150k miles, and they were pretty hammered by that point. The transmissions are not the best.
Toyota and Honda make better cars than their domestic counterparts. My folks now have a Toyota Sienna that has been a solid vehicle. I have heard nothing but good things about the Honda Odyssey, but don't have one in the family. Generally, the Odyssey is considered the best of the minivans through my past research.
Used minivans are also pretty cheap for the utility they provide and are built specifically to haul families around. They get 20+ mpg. When not hauling kids, the seats can be taken out/folded into the floor and you have more enclosed cargo room than a small truck with a shell would provide. Seems pretty good to me for your criteria.