I've worked on two different Caravan thingies. One was a 1999 Plymouth Voyager, and one was a 1988 Dodge Caravan.
Knowing that, I'd go with a Durango in a heartbeat, if I had to choose between a Durango and a minivan. They get about the same gas mileage as a minivan (or would, once I got done with them), and they're a lot easier to work on than a minivan. Of course, that's just speculation, as I've never actually worked on a Durango. However, I've worked extensively on my Quad Cab Dakota, and I can't imagine that a Durango would be substantially different.
I only support MPGuino - contact me at tomcat dot ak1972 at gmail dot com