Oinick, very nice thoughts and observations!
I am curious; do you have Adaptive Drive (within Dynamic Driving Control) in your wife's 740i or maybe in your 535i GT? (You have not mentioned Comfort chassis setting in your GT(?) and I assume your GT does not have it.) Is it possible that Adaptive Drive might be the reason for the difference of ride quality between both cars? (In my 530d GT I can feel very noticeable difference in ride on the highway at high speeds when chassis (AD) is set on Comfort: the car glides smooth like a heavy road cruiser.)
Regarding shifting: in my 530d GT I do not experience a lot shifting at low speeds. In contrary, 8 speed transmission is nearly unmistakably accurate and even forgives all my mistakes at manual shifting (for instance when I kick down in order to brake and then turn on automatic shifting and immediately step on to accelerate).