I've been driving Honda Odysseys for 14 years. When I had twins, I loved that I could take out the passenger side chair of the 2nd row because I put the twins in the 3rd row so I could climb in the car to get them fastened in their car seats with no problems and was protected from bad weather also. When I had my third child it still worked great because the twins could climb in and out with ease and I climbed in to fasten the seat belts. Nice and roomy inside and LESS FIGHTING OVER SPACE. We only put the chair in if we have more people with us. My twins are 14 years old now, but we have a small toy-breed dog. She loves her car carrier which sits right behind the passenger seat since we keep that chair out. This keeps the little 4lb thing safe and happy. The video I watched announcing the Model X showed that all the seats can lay flat, but I don't know if they can be done individually. I really need to be able to remove the one seat or have it lay flat.
The other feature I loved about the Odyssey was that it had the pop-down mirror where you can store your sunglasses. These simple features can be important to people. The initial decision between the Odyssey and the Mazda minivan back in 1999 was that Honda had the pop-down space for the sunglasses. And I stayed with the Odyssey since.
So the two things I absolutely must have is removal (or fold down) of the 2nd row seat and the mirror with the place to hold the sunglasses.