I gave some more thought to this, and I'd like to toss out some possible definitions.
Wagon: a sedan except for the cargo area.
Raised wagon: the suspension is raised, but the floor-to-roof measurement is the same as a sedan. Outback, Cross-Country.
Crossover: car-based, but with the roof raised relative to the floor. The floor may be higher off the ground than a sedan (i.e., Tribeca), or it may not (i.e., Ford Flex), but there's a definite addition of height from the vehicle's floor to its roof.
Van: a subset of crossovers that have sliding doors. Note that this would NOT include either the first-generation Odyssey or the R-Class.