Biggest headache? The kids buckling themselves. The seatbelt always locks (they pull too fast), the buckles get smushed into the seat bench, and before you know it I have exited the car, just to help them put it altogether.
As a tall person, I am excited that Elon is tall and getting them to consider the problems of not being average height =)
Most everything in my world was designed for someone 3-4 inches shorter than I. I kid with my wife if I ever build my own house (post kids), everything will be taller.
To be fair to Tesla, Elon Musk did address this around two-thirds of the way through his presentation yesterday, saying "when the minivan door is open I can't even get through that space." I suspect he'd also say the Model X's doors provide a vertical opening in addition to a side opening, which can be useful for adults in the second or third row.
On the other hand, I've driven a Honda minivan quite a bit and I can't think of any times when I couldn't squeeze through the available space when the minivan door was open in a parking lot. So there is a bit of solving a problem that may not be very much of one.
tesla model S width 77.3"