I must just be very lucky because neither of my older 2 complained once about being rearfacing until 2yo. In fact, we initially turned my son FF at 21 months because we thought he'd want to watch a movie on a long drive and he asked us to switch it back! He hated how his toys fell to the ground FF and he loved looking out of the back window when he was RF (we have an SUV, and he was RF in the center, so he had a perfect view!). So we turned him FF and kept him that way for another 6 months, when, again, we turned him to watch a movie on a long car trip. He did ask me to switch the seat back again, but I didn't feel like doing it at the time and he seemed to forget about it so we left him FF.
And regarding younger siblings, that hasn't been an issue for us either. My above mentioned son is my 2nd child and he was RF sitting directly next to his FF older sister, and like I said, he preferred RF. My 3rd is 14 months tomorrow and still RF while her older brother and sister are FF. She actually seems to enjoy RF as well, probably because her sister in the 3rd row is right in her line of sight (and she LOVES her). And her brother sits across the aisle in the 2nd row (the baby is behind me in the 2nd row), so she can see him too and he can hand her stuff.
Regarding kids dying to get out of boosters, again, just lucky that isn't my family. My 7yo is 50" and 52lbs and still harnessed in her Britax Frontier85, AT HER REQUEST! We were out of town last week so we use a backless booster when flying (not on the plane, just that it's easier to carry around than the Frontier). I was putting the Frontier back in my car on Sunday and asked her if she wanted me to leave the harness straps in, or take them out so she can use it as a booster and she said "Leave the straps in. I like the seat as it is." She made the same choice last summer, at 6.5yo, when I got a new car and asked her how she wanted it installed.
We send her with the backless booster to friend's houses, but we have had friends in our car and they have seen her seat and never said a word. Another 7yo in her class sits in the same Frontier85, also still harnessed, so it really isn't that strange. When she was 5yo, she did have 1 little boy ask her why she still sits in a carseat and she told him, "This kind of seat is safer than a booster seat and I want to be safe." So in her case, if she still needs a booster past 9yo (which I don't *think* she would, as she should be about 57" then, based on her growth curve), I don't think she'll object.