Do you like to rip the bandaid off quickly or slowly? Either way will be a challenge with a 2-year-old. I always pick flying--but my family is in NY, so DD's been flying regularly since she was 3 mos old. She now (at 23 mos) understands that she's going on an airplane, knows the drill, we bring lots of food and snacks, and it's all okay. When travelling by myself with DD via plane, I'm super anal about packing super light, so I can manage bags and DD as well--it helps that amongst old friends and extended fam, we can borrow most of what we need once we're there.
We did drive from McKinney to Tuscaloosa, Alabama last summer to see DD's godparents. DH and I were together, and 2 people were definitely necessary. My DD is SUPER active, doesn't like to sit still at all, and maxes out on DVD's after 30 minutes. So DH and I traded off sitting in the backseat to play, read, sing songs--and we still stopped every 90-minutes to let her out to run around. We divided the trip into two days, and a 7 hour drive took 11, all told, after all the stops. But our DD is on the super active side--if your kid will sit and watch a whole disney movie, for example, it's a different story.
In your situation, I would pick the plane, but it depends upon your kid's temperment. Yes, it will take a while by the time to get to the airport early, etc, but you can give your DD most of your attention most of the time, instead of trying to drive and entertain her at the same time. GL!