Well young lady, you are about to get a TON of (mostly) male, (mostly) BMW oriented advice about one of the most personal and costly decisions a person can make. Here is my take: You could hardly have chosen a better economic time to have become unhappy with the Z3. The Fed just cut short-term rates again and interest rates are extremely favorable right now. You are extremely lucky in that you have a board member nearby that you should be able to trust to help you make this decision. I think I would go to him and try out every flavor of car on his lot. I think that I would start with the least powerful and go right up the line till you get to one that seems to fit your requirements for utility and horsepower. You have not ever mentioned a SO (that I can remember) but even if you have one, I would try not to let that person influence your decision overmuch. Just find what you like and buy it. You have mentioned the M3, and of course, it would be my personal favorite. He is the only car I have and is my daily driver. He is perfectly happy being flogged along in heavy traffic and seats 4 with a decent sized trunk.
It was very disturbing to read about the man winking at you. I assume, being female, that you have had this happen before - But a BUICK?? Shameful!
A friend will allways try to help you up when you fall. If I can't get you up: Hell, I'll just lie down with you.