I have a GMC Acadia and love it. Just like you I have 2 children in car seats (2 1/2 yo and 10 mos old), and a 77-lb dog.
We got the captain seats for the 2nd row so 1) the dog can sit between them 2) makes it easier to get to the 3rd row, or I can sit in 3rd row and entertain them if needed on long road trips. Most of the time our 3rd row is down, as I store the stroller in the "trunk," fit groceries etc. It's been great for the many long road-trips we take. When up, the 3rd row isn't huge but adults can sit back there if needed. For example for Christmas me and my father sat in the 3rd row on the way to church as my mom and husband were in the front seats, and the girls obviously in the 2nd row.
Only "bad thing" on the Acadia, and it's silly, is the placement dry cleaning hooks. They're in the 3rd row so not easy to get to from the trunk or the 2nd row. But pretty minor "con". Good luck!