I had this dilemma a few years ago. I was all set to get a GTV as my main car, when my beloved dropped the bombshell. I put off the decision until after my daughter was born. I tried to fit the infant carrier in, but failed miserably (it would fit in the front seat, but I| wasn't happy with doing that)
The other big issue was the boot space, or rather the lack of it. I seriously considered sawing the legs off my daught...
sorry, had to stop there, my other half came upstairs!
In the end I tested a GT, obviously a lot more expensive than the GTVs I was looking at, but it's almost as pretty, and a hell of a lot more practical. I was after a V6 GTV, but settled for a diesel Gt (yes, I know..)
My other half had a Mini Cooper (a proper one, not a Kraut imposter) and she found the same problem with space, and also safety with her car. In her case she opted for a Golf (couldn't persuade her to get a 147 at the time)
Interesting thing is now SHE wants a GTV. First born is now nearly three, and approaching the size that she'll only need a booster seat, we haven't used a push chair for the last 12 months or so and it actually seems that a GTV is a real option, now as a second car.
I can't wait