I want to start off by thanking everyone who has chimed in already, and I look forward to other thoughts and opinions.
I posted this message here and on the Transportation board and have gotten some good feedback (even if it's one of people thinking I've gone insane...

).
When I was married to my first wife, it was just the two of us, so flying down and a week or two of a rental car wasn't that much of a concern. Sure, we had to save, but add in five kiddos and boy howdy does the cost to fly skyrocket...

Hence my posting on the DISBoards.
The furthest I've ever traveled by car was about 975 miles, way back in 2001 when my ex-wife, myself, and four other friends drove two vehicles down from Oregon to DL. That trip took about 19 hours (Google Maps says it should take about 16, so with stopping for food/gas/potty, everything seems in order with their estimation, if driving non-stop).
As for the suggestions to travel to DLR...well, it just doesn't compare to WDW. All of the children have been to DLR, so it's not really an option (at least at this point in time). WDW is much more appealing, especially to DW and the teens. I've always known that flying would be the way to go, but it's such a sticker shock to DW. I said that I would do my due diligence and do as much investigation into other alternatives as possible, and do it I shall!

:
I truly do appreciate all of the friendly information I've been given and I'll come back with more of my own, once we nail things down a little more!