The wagon is great not only for the ability of fitting 3 car seats in the back (3intheback) it also allows for mountains of stuff in the boot. When the missus said we really needed a wagon, this was pretty much all i would look at, along with the Legacy.
In saying this though, the rear seats don't really have as much space as you'd imagine on a wagon of this size. And I keep rubbing my pants on the rear wheel when i put my little one in her seat, black marks on the pants just before going out isn't a good look. The wife does the same so i'd be interested if any other people have that problem.