Well, it's always cheaper for us to fly back to SD than drive - since it takes 3 days to get there in the car! But it might not be so clear for you - a report from MSNBC:
There are several major factors that influence the cost of a trip, including how fuel efficient your car is, how far you're traveling, how many people are traveling with you, and whether or not you can find good airline prices.
Here are the four things you'll want to consider as you do the math:
Step 1: Determine your vehicle's gas mileage.
You probably already have a good sense of what kind of gas mileage your car gets, but if you want to be really precise, a good resource is the EPA's car comparison calculator, which provides miles-per-gallon estimates for city and highway driving.
Step 2: Check gas costs.
Determine how much it will set you back to fill up your tank on your trip. The best source for this is AAA's Daily Fuel Gauge Report, which provides detailed gas prices in hundreds of markets across the U.S. Just punch in your origin, destination, and your vehicle's year, make and model and the website will churn out an estimate on fuel cost for your trip.
Step 3: Factor in the cost of tolls and hotels.
Don't forget to consider the amount of money you’ll be spending on tolls and, if you're traveling long distance, any hotels you might need along the way.
Step 4: Check airfare costs and compare.
Last but not least, check how much it will cost for your party to fly to your destination and do a cost comparison. Start your fare search with sites such as Kayak or Expedia, but keep in mind that not all airlines share their data with online travel agencies...and always check Delta.com.