Anyone with knowlegde of the overnight autotrain from Virginia to Sanford, Florida?

Yes but what kind of knowledge are you looking for? My grandparents regularly take it. They drive from CT to VA and hop the autotrain with their car to Sanford which is just outside Orlando. They have a fear of planes that's why they take it. Never had a problem with it.

Is there a website? How long does it take? How much does it cost?

Check out www.amtrak.com. There is a section devoted to the autotrain and gives quite a bit of info. Last I knew they had a rail sale with a good price for the trip. Check it out under specials. We've taken it northbound once and will be back on it southbound in a couple weeks. You leave at 4:00PM and arrive the next morning at 9:00. It's non stop and includes dinner and breakfast with complimentary coffee, tea, etc throughout the trip. Getting a compartment is very expensive, coach seats are fairly comfortable and its only one night. Not the best sleeping arrangements but sure beats driving 900 miles on I-95!!
Good luck.

I've an acquantance who took it (by himself) for a 1 week trip to Florida, driving from Albany NY to VA to catch it. He enjoyed it very much, but in retrospect thought he should have just taken Amtrak entirely from Albany to FL & rented a car when he got there. If one has a specialty vehicle, or is on an extended stay, then it makes more sense than using it for a short stay when you must drive so far just to board it. I'm surprised Amtrak has never found other boarding locations futher north, and west.