When we were getting ready to have child #5 I realized our Yukon XL was not going to cut it. I found a 2014 model year Chevrolet Express used in the spring of 2014. It was from a rental fleet and had 16K on the odometer. I paid half price for a current model year vehicle! It is a 3500 with the 6.0L gas engine and 6 speed transmission. It is rated at 9600# towing, and it does really well.
When I was looking for a new vehicle my wife totally rejected the idea of a van. Then she saw how many car seats fit in it and changed her mind. We have a full size, commercial grade dog crate in the back, 5 car/booster seats, and plenty of room. As the kids grow out of car seats and sit in normal seats we have even more room. Since it is built on a full ton frame with 80 PSI in the rear tires it is a rougher ride, but you get used to it.