After seeing the picture of the red 900 wagon... it actually blows my mind that Saab would not build this to compete with the Volvo wagons of the same time period. Definitely a more attractive Swede! (and I'm a Volvo fan...)... Actually one of the best looking wagons I've ever seen!
The Ferrari 456 is a huge favorite of mine, loved them when I was a kid... The wagon is like icing on the cake, looks awesome - and serves the 2+2 purpose of the 456 even better, with real room for those 4 people to take that car on an epic trip.
The S-class, and 7-series actually take to wagonizing quite well. They both look like factory models. Surprisingly the 928 look great too!
The American muscle cars look too 'mommy mobile' in wagon form... definitely need to be left as the awesome muscle cars they are. That C3 Corvette is absolutely fugly...