"The decision is definitely a GMC pickup truck with cap, 4 doors for 2 car seats and it must be a 4x4. My wife will be driving it 20 miles per day with children."
Why limit yourself to one choice? The GMC Duramax diesel is a great way to go but so is the Ram Cummins. Especially the Mega Cab as mentioned above.
BTW, the 454 has gone the way of the dodo bird. Today's smaller gas engines have more horsepower, more torque, and get double the gas mileage.
Heck, my old Tudra Crew Max (same cab as the Dodge Mega Cab) had 381 hp and 401 ft lbs of torque. Got around 14-15 mpg daily driving. Fantastic tow vehicle too in its class.
