I truly appreciate all of the helpful input I have received from you guys. I have looked at several of these vehicles in person now. I will give the perspective of a mother of 4 kids who are not babies/ toddlers but still many years off from driving themselves. Here goes my review of third rows/cargo areas.
The Tahoe/Yukon (2015) :
These are really attractive vehicles, but the 3rd row is ridiculous. No one taller than 40 inches can sit there comfortably. Also the cargo room with all three rows in use is pitiful. I didn't even test drive it. The rest of the vehicle is very nice.
The Suburban (2018):
The interior is beautiful. I can see why people prefer it to the Expedition-especially up front. At first the third row looks promising. Then my nine-year-old gets in the 3rd row behind one of the second row seats and asks Where do I put my feet?" The second row seats do not move forward. I don't know if this is customary across all Suburbans, and I would like to find out. So, I didn't test drive it either. This was a new vehicle. There seems to not be a lot of used Suburbans in my area except really old ones, which I assume speaks well for the vehicles.
The Expedition (2017):
Here is the obvious 3rd row winner. However I think for a large family only the EL would work unless you don't mind having everyone ride home with groceries in their laps. That said, 3 larger kids across in the 3rd row actually works, and I liked that the 2nd row could slide forward to give additional leg room. The vehicle drives fine as most newer vehicles do.
The Bad: I really don't like the front passenger area of the vehicle. I felt like I had to reach around the shifter to access the climate controls, and there were too many buttons. Also, the center console is huge, but offers very little space. There is no place to put my purse except the passenger seat or the floor in the passenger seat, which is awfully far away from the driver. The vehicle is nice, but definitely not as nice as the inside of the Suburban. I am hoping to see an older model without an infotainment screen. Maybe it won't have so many buttons.
The Chevy Traverse.
If I didn't need to tow ( and we are RV'ers/campers), this would definitely be a contender. There is both kid room and grocery cargo space. The interior styling is nice enough particularly when considering the cost difference between it and an Expedition, Tahoe, Suburban, etc.
I hope to get to check out the Toyota Sequoia today or tomorrow. I just found one in my area.
Right now my best option is the Expedition.