Hi neighbor! The auto train was an easy way to get there, but you have to consider your start date (boarding date) a wash... we drove down the night before as we were afraid to run into traffic on the way to VA and miss the train. We got on the train 2:30pm, ate dinner early I think like 5:00pm, watched a movie in the lounge car (people are so nice on the train)! Chatted with some folks, went to bed at 8pm (kids time since we had a family suite, woke up at 7am for breakfast and we were in FL by 9am! we had the sleeper, but it was small. We have traveled it 3 times (2 with kids and sleeper, once just adults and coach), I can say, all 3 times the coach seats were empty and families could really stretch out. The biggest concern about coach, for us, would be kids wandering off while we were sleeping, so I feel that one adult would have to be awake at all times... but thats just me. There is an entire Autotrain thread which gives good info. I considered it again for the way down this year, but I don't think we can squeeze into the family suite again, and coach is out with them being so young (hard to keep quiet)
I don't think I could make the drive on my own... unless I was breaking the drive into only 7-8 hours limit a day. But, the most I have ever driven on my own with our kids is 6 hours.
As far as the mapping program, we are going to use our GPS, but I did find
www.freetrip.com that maps out the hour markers, which is nice for hotel planning.
As far as cheaper flying, I don't remember what your party size is, but I found cheap flights out of Newark and Philadelphia... under $200 a person. Only a 3 hour drive for us, but DH hates to fly. I asked again and he said we are driving or not going.
Good luck to you, tough decisions!