I am seeking a used Sienna with 8 passenger config with only two kids. You can carry more friends or most of another family with 8 passenger. The middle seats remove very easily to make a 7 passenger configuration as each one is invidual. The seats flip very easily(spring loaded) to access the rear of vehicle.
Try both out but I rented 7 passenger and 8 passenger over a few times and much happier with 8 passenger version.