To summarize, I just got back from my 2,776 mile trek this week. Everywhere except the Atlanta - Charlotte portion is now well covered with Superchargers. Screw a bunch of finicky CHAdeMO chargers - superchargers are the game changer here.
I was able to do a full Range Charge in Charlotte (which at this point in time shows 249 Rated Miles with Range Mode OFF in my car) and make the 245 mile trip to the Decatur, GA Supercharger without stopping for any boost. I had 10 Rated Miles left when I pulled in to the Decatur SC and that included sitting in stopped traffic on I-85 for about 30 mins. with the A/C running for a multi-car accident. I watched a few miles tick off sitting there (and that, frankly, was the closest thing I could say gave me any anxiety on the whole trip). It was really ticking me off thinking I've gone 65 MPH on this entire stretch and gained about 13 miles over my original Rated Miles and now I'm going to lose them sitting stopped on the interstate. Without that I believe I would've pulled into Atlanta with 13 or 14 miles remaining. Also, I got to Atlanta on a Friday at 4:45 PM - the traffic was horrendous and I probably went a mile or two out of my way to avoid the biggest traffic mess on I-285.
Bottom line, if I can do Charlotte ---> Atlanta in my P85D with 21" staggered wheels & tires it should be easily doable in any 85 in summer in good weather.
The rest of the trip I did 70 - 80 MPH and averaged 317 Wh/Mile for the entire trip. It had actually gotten down to 314 Wh/mi by the time I arrived at the Mobile, AL Supercharger but for some reason the last 144 miles on my trek west back to New Orleans on I-10 used a lot of energy and I ended up at 317 when I got home.
All in all I gotta say the Model S is a great way to do long distance travel.
Mike