Also, consider other factors:
-- Time. Do you have the time to spare or will it cost you valuable vacation time? (We're both teachers, so we could manage the time over the summer. For other people, it would make a real difference.)
-- Is your car up to the challenge? Is it big enough to give everyone the room they would need for such a long drive?
-- Are your kids up to the challenge? Or will they drive each other and you insane on the trip home? (I imagine that getting there will be relatively easy for them.)
-- Factor in an overnight hotel stay (and pre-plan it) and meals along the way.
For us, from Long Island, the better solution was still flying. But you're right to look at all your options.