My tupenny worth
A little late to join this thread admittedly, but here's my opinion for what it's worth;
I have a 2.4 JTDm 159 Sportwagon (twin exhausts), my wife has a 1.9GT Blackline (red stitching on seats). I personally love both cars, however, reading your needs, you have definately made the right choice. I love driving my 159, but I have to say, when I'm on my own driving, the GT does have more driver appeal. Furthermore, if we choose to go out in the GT, our 3 children all fit in the back ok. Not as much room as my old Passat estate, but in fairness, not much less than my 159 either.
In summary, enjoy your GT, and when you have a family and need something slightly bigger, pass the GT to your wife and get a 159 Sportwagon.
You won't regret either.