I feel your pain and was in the same situation except for the parents. I ended up buying the G35 with no intentions on modifying just as you said, let me tell you.. you WILL modify the car, dont even try to convince yourself otherwise.

I had the idea to wait for the GTR myself but it supposedly wont be revealed till about 2007 and you know nissan/infiniti will put a crazy mark up on them when they do come out. At this point the only thing that would appeal to me is the AWD, other than that you'd probably be buying something similar to what you could do to the G35 at a cheaper price.

A used G35 wouldn't be a bad route to go, many owners who have taken care of their car are looking to trade up to an 05 because they think 298hp is so much better than 280hp (although there is a loss of torque) and plus the brembo brakes aren't an option any more. I say go with option 3, get the G35 as the NICE project or even just a weekend car and keep a daily driver.

And I do understand the parent thing, I bought a bigger house to accomodate my mother rather than have her go to one of those senior homes, I've had to fix phone lines in those places and I couldn't imagine her having to live there.