No matter how anyone prices it, nothing beats driving for our family of 6. Even if you take into account the price of hotels, gas, restaurants along the way, there are many expenses to flying also, including that you have to rent a car.
An added bonus is all of our kids LOVE driving, they love how the scenery changes, they get excited as we enter each state and we see the signs "Welcome to Virginia", etc. they love the Welcome Centres. We love stopping at outlet malls. To me the journey is as much fun as the actual trip.
We drive 77/79 and have made our own mini-book on the rest areas and restaurants along the way. Makes it so much easier.
Plus when you drive, you can just about bring as much as you want, no need to worry about packing it all into 2 suitcases. We even make a major grocery stop before crossing back into Canada