Hey late to the party, sorry. I have two kids. When we were looking to buy our ST at the end of 2019, I originally ordered a bench seat thinking that was best. I ended up swapping to captain's chairs, which I think worked out better. The kids were rear facing for a while - they are now both front facing. One is 4, the other is 3. The kid seats are in the captains chairs. When the grandparents visit, one of them sits in the 3rd row with my wife, the other up front with me. There's not a ton of room in the 3rd row, but for short trips out to dinner or whatever, it's quite serviceable. The way they get to the 3rd row is to climb in front of the captain chair on one side, then go through the gap between them to the back. No folding or moving of the captain chairs are necessary (though they can slide forward with the car seat installed to give a little more leg room for 3rd row people). Once they are back there, the kid gets put into the kid seat. If we put the kid in the kid seat first, his legs would get in the way of people climbing by to get to the back. So 1 kid goes in last after the people have loaded into the back.
This works very well for us. We could put the kid seats in the 3rd row, my particular kid seats are designed to fit 3 across (Diono Radian 3RXT), so they would fit together in the narrower 3rd row. However, getting back there to get them in and out would be a huge pain, and they are not reachable from the front seats at all, so if they drop something, the front passenger can do nothing to help out.
I know the OP already bought their ST (congrats!), I'm just posting this here for any other parents wondering or with questions. I went through the same exact process back in 2019 when buying our ST, to the point of even bringing a tape measure to the dealership to see how kid seats would work. What I described above works pretty great for us. We only have the 2 kids, and will not have more. If a 3rd kid were added to the mix, then I'm not sure captain chairs would be best the option.