I looked at your routes on Mapquest, and it looks like it's going to be three long days. About 12 hours each day. One car or two? If one car with four drivers, it's doable. But I'd like a day or two extra to possibly do some sightseeing along the way. After all, you're be passing by such landmarks as...Graceland (southern route), Gateway Arch (northern route) and Lookout Mountain (northern route) I wouldn't worry too much about cell phone coverage. Assuming you have good cell phone coverage and not Willie's Bargain Basement coverage, you'll be fine on interstate, and I think you'll be OK off the interstate as well. Southern route is shorter, but it takes you off the interstate more. Northern route is more interstate (only about 50 miles off interstate vs. about 900 miles off interstate on the southern route). I may take one route down and one route home. If you're really worried about being in the middle of nowhere, I'd take the northern route. At least you'll be on interstate for over 95% of the trip.