I am no 370Z owner, but I do own an S2000 which is my only car. At two points in my nearly 4 years of owning S2000s, I have had other cars. I only got them because I liked the two rides I picked up. I never felt as if having a sports car as my daily driver was a problem. I don't move every other week, and I don't have a lot of friends bumming rides. I find that my S2000 holds enough groceries and what not that I have never had a problem. The 370Z, from what I have seen, has more room than an S2000 in most aspects, so I think I would have no problems with it as a daily driver.
It seems like it all comes down to you. In the end, only you can decide if this car is suitable enough to be driven as your only car. If road noise and comfort are a concern, I think you would be less than happy with this as your only car. In my opinion, it is a sports car and not a comfortable cruiser and certainly not a hauler in any fashion. Tell your friends to take a cab to the airport....
Life is too short to make decisions based on what your friends need. Unless they are helping to pay for the car, I would not base the purchasing decision on whether the car has enough room for a hauling a friend's stuff.