There are times when driving is necessary. For the most part, if I can fly for close to the same price it's a done deal. With gas prices teasing at $4 a gallon in my area it is still pretty expensive to drive. We were pricing renting a van and the cost of gas to drive from Cincinnati to Tampa and it was between $900-1000! So for a family of 5, $200 per person to fly and it comes out to be the same amount. If you have 1 or 2 people going it is an even better equation. Yes, you still have to factor in the cost of getting to the airport, parking (maybe), car rental or transportation at your destination but there's so much less stress andyou won't arrive at your destination exhausted from a nightmare of a drive.
Yes flights could be delayed or cancelled. But what do you do if you are traveling down the highway and there's an accident ahead of you that shuts the highway down (not even addressing getting into an accident yourself) and you sit in your car on the highway for hours? I would much rather be stuck in an airport than in a car.
Weigh the pros and cons and make the best choice for your situatuion. Flying is (at least for now....) more affordable than it seems.