Here's a couple scenarios at opposite ends of the spectrum, just for kicks. The first is still using DC as the departure city (850 mile drive) as an example. Let's say the airfare is a bit higher, $225, instead of $179. Still a family of 4.
Super budget - Drive straight through, bring your own food.
Gas - $106.5 X 2 (for both ways) = $213
Motel - $0
Meals - $20 (cost of food both ways)
Depreciation of car = $100X2 = $200 (you drive a car that is over 60,000 miles so depreciation is minor).
Opportunity Cost of Free Time spent driving = $0 - you enjoy the road trip, the whining kids don't bother you and you consider it a bonding experience (or don't value the free time spent doing other things than sitting in the car.)
Parking - $0
Total = $433, Savings is about $553 driving versus flying ($225X4 + 2x$43 = $986)
You do a 4-day/4-night stay with 3 days at the parks in a budget hotel and eat fast food or buy your own groceries the whole time. Say $600 for passes, $40/day for meals/snacks, $100/night for motel including taxes = $600, $100 for a few souvenirs = $600 + $160 + $400 + $100 = $1260 + $433 driving costs = $1,693. So in that case, the $553 you save represents a savings up 24% of the total cost of the trip had you flown.
Now let's do another scenario. Something closer to my actual scenario which is different than the what I tried to make as the 'average' scenario I used at the beginning.
I'm in Seattle so it is whether to drive or fly to
Disneyland. I just booked tickets a week ago to LA for $218/person. Figure the same $43 each way for shuttle. The drive is 1162 miles os about 4-5 hours more than DC but I know a lot of people do it. We would drive our 2004 Honda Pilot which gets 24 MPG highway and has 30K miles on it and cost a little over $30K.
Gas - 2 x $121 = $242
Motel = 2 x $110 = $220
Meals (one extra meal than DC due to longer drive) - Breakfast $25, Lunch 2 x 25, Dinner, 2 x 60 (I tip well and we would like a decent sit down dinner for 4) = $195
Depreciation - I'd say the car will depreciate an extra $500 at least by putting the extra 2,200 miles on it
Lost Opportunity Cost/Increased Risk - I like spending a lot of time with my children, although in a pool, at the beach, or in the park. Not in a car. I have almost unlimited vacation time as I work for myself and can work from anywhere in the world - just need an Internet connection (so I can get a few hours of work in while the kids are asleep at night if I need to.) I like driving and am a good driver but know the statistics and prefer to be on a plane. The flight is about 2.5 hours. We get to the airport 1.5 hours ahead of time and the airport is 20 min from my house and 40 min from the park. So we are looking at a total of 8 hours travel time to fly versus about 18x2 = 36 hours of driving = 28 hours of extra time in a car instead of driving to and being at the airport or on a plane. If someone asked me you can either drive down I-5 for 28 hours for free, playing games in the car and singing songs part of the time, and listening to your children (and sometimes your wife) whine and bicker the other part of the time, or you can pay me $x and the drive will take 1 second and you can spend the saved time swimming and riding rides with your kids (or making money) I would say yes to $40/hr or more. So my lost cost of opportunity for me personally is at least $40/hr = $1,120.
Most of the hotels in the Disneyland area cost $10-$15/day for parking and I'm going to be there 4 days.
Parking - $40
So total costs in this scenario are:
Driving = $242+$220+$195+$500+1120+$40 = $2,317 (if you negate the cost of lost opportunity, which I feel is indeed a real cost, and say the 28 hours extra hours spent in the car was extremely enjoyable every minute of the drive, it would still be $1197 in this scenario - but hey, one person put the opportunity or inconvenience cost at $60,000, so my $1120 pales in comparison!
Flying = $218x4 + $43x2 = $958
So driving, TO ME IN MY CASE, is $1,358 more expensive than flying, $239 moe expensive even if I totally disregarded the cost of lost opportunity/inconvience of 28 hours in the car.)
So there you have it. One scenario, probably the best case scenario if you live more than 500 miles from the park, you save $467 or 21% of the total trip cost even if you are a penny pincher by driving instead of flying (for an average 4-person family). It would be more for a larger family, less for a 2 or 3-person family.
The other scenario, you lose $1,358, all things considered. So you see, the initial DC scenario I proposed is sort of an 'average' scenario. If you were driving a Porsche SUV with higher depreciation and ate in the most expensive restaurants and stayed at the most expensive hotel and only drove 6 hours a day instead of 9, then the driving would be even MORE expensive. But that would be an anomoly like driving a Prius 17 hours straight through without stopping at a restaurant.
The big point is, most everyone's particular situation is different but will fall somewhere inbetween these two scenarios (for people that live over 500 miles away from the park). Most of them will NOT be near these two opposite ends of the spectrum. In one case, $500+ is saved, in another $1,300+ is lost. So it is still my initial contention that for the average size 4-person family or smaller, most cases, NOT ALL, driving will not save a SIGNIFICANT amount of money, ALL THINGS CONSIDERED.
This is probably one of the biggest decisions involved in planning your Disney trip. I bring it up because I believe things are not always what they seem, face value. I don't expect a bunch of people to be posting here saying, gee you're right, we are a family of 3, or 4, or even 5 in some cases, and we made a dumb decision and drove. It isn't necessarily a bad decision. I do expect to see a lot of posts with individual scenarios that significantly differ from the one I started the thread with and it is very interesting to read about them and learn from them.