You have already pointed out one model that would work the 351BHT. I have the 09 Sierra 351BHT and love it! with the dual slides in the back you can sleep 6 just the the back with plenty of room to spare. She is very heavy though so you need at least a 1 ton TV. I pull with a 1 ton GMC Sierra dully diesel. Since your family is bigger then mine I think this is where you might have an issue. You might need to look at a used Ford Excursion diesel to be able to tow that much weight and also have room for the kids and pups.
Here is a pic of the rear bedroom:
Cant zoom out to get entire room. this is one side and the other is the exact same.
This is the entertainment center in the same room....
Hope this helps!
Iceman