I think an '05 wagon (gotta have the new interior), with a full STi swap (engine, tranny, hubs, brakes, suspension, and the wider fenders
), a mild exhaust, VF22, and maybe a rear swaybar, would be the ultimate daily driver.
You'd have a decent looking car (not quite as nice as older wagons, but still not bad) with a sunroof, heated seats/mirrors, nice interior, tons of space, with STi performance. The only thing that irks me about the wagon is the lack of fender flares.... they would look soooo much better if they had a bit of wide-body to 'em like the Audi RS6 wagon, for example.
So, I'd totally roll an STi converted wagon as my daily driver / winter beater, as long as I had a Porsche Turbo for the weekends.