I'd consider front fender braces a more worthwhile investment than a front strut brace, although I never got the chance to try them on my car. At $90, they're about the same as a front strut bar.
As stated, the wagons could definitely benefit from a rear bar, as they don't have the chassis members extending between the strut towers there like the sedans do (right behind the back seat at about shoulder level). How much of a difference did yours make, Zach?
Subarus are quite rigid from the factory, though. That's part of the reason they have sill-less windows, since the door frames and chassis are already so rigid, they don't need the added weight of the door sill. During my sub install, I was amazed at all the bracing throughout the car just underneath the trim paneling.