I drove to GA from UT which is a 1800 mile drive when my son was 11 months, the only time he would really fuss was when the sun got in his eyes, other then that we had snacks out for him and would feed and change him when ever we stopped for gas or when we needed to go to the bathroom or ate. he was the same way on the drive back to UT I was amazed.
i took my daughter from md to fl right before she turned 6 months old. we took a flight, she nursed and frequent... so i decided flying would be best. i had a layover since i did cheap tickets, but she nursed on every take off and never once cried during any of the flights
My mom, brother, sister in law and I drove to Colorado with a 3 and 2 year old and a 4 month old. It took us 23 hours to get there, but it really wasn't bad. I drove two weeks ago to Michigan by myself with a 7 month old. She slept the whole time and I only had to stop when we needed gas. I would then change her and feed her and she would go back to sleep. I'd rather drive then fly if I could.