We drove last September from NJ- about 18 hours on the way down- broke it up into 2 days on the way back. This year we are flying- I figured we'd save about the same $400 if we drove- but the following factors are why I wouldn't drive.
First, wear and tear on car- an expense whether it seems concrete or not. The minivan was trashed and I mean trashed when we got back from snacks, entertainment, drinks, you name it. Plus it now had an extra 3000 miles on it.
Second, all the small unforseen expenses to occupy two young children in the car- puzzle books, games, snacks, candy, and all the stuff that entails.
Third, food on the way down and up- we packed lunches for the way down- but of course still had dinner, then the way up had to pay for all the meals plus one night at a hotel.
Fourth, putting yourself in harms way. I think statistically its safer to fly then drive, but also when you think about it, some of the rest stops can be scary and alot of hotels off the highways can be kind of scary too.
Fifth- time is money. My DH and I figured out our time is worth money too. Think of that $400 dollars spread over 38 hours (both ways)- that works out to 10.52 cents for the whole family per hour of traveling. OK, say by the time you take the plane and get home round trip the whole thing is say 12 hours total- that's still 26 hours extra of driving, divided by 400- 15.38 per hour saved. My time is worth more than 15.38!!!!
I have strong feelings about driving long distances, to me they are boring and endless. You are exhausted when you arrive and then have that drive to look forward to when you are leaving. A lot of people I know drive from NJ and they say, its not problem, its easy- but unless you love sitting in a moving vehicle and staring out a window- I'd definetly fly! Good luck in your decision!