Thanks @Tesla S1: My first adventure in my P85D going long distance was great. I had to go 186 miles between SCs at longest stretch and no issues. I set to sport mode & then range mode on, kept my speed at the legal limit or no more than 5 miles, outside temp was 75-80 degrees and kept fan at 4 with temp set at 72. The whole key was (as advised) was setting first, the NAV to the SC that was my intermediate goal (waypoint) and then watching my electrical usage by monitoring the trip graph. I would also look to see how many miles left to go per the NAV and the rated miles to get a sense of where we stood. My personal comfort zone became to have a 10% reserve per the graph when reaching the SC waypoint. I did get down to 8% a few times on the graph while driving ealy on in the trip and then slow down in 5 mph increments until we would get the trip graph back to 11%-12% range. It was simple and straight forward. The comment to not over think the trip was the best advise I got, just let the trip graph guide your driving.
On the return trip, I got a bit more confident and charged to just 240 miles rated range (vs 256 max I get) for my 186 mile trip to next SC. It took 55 min for the Supercharging to get my P85D from 72 miles of range to 240 miles of range at the first supercharger and it was estimated to take another 15 min to get to 256 miles of range, so figured 240 rated miles was plenty to go the 186 miles. Three hours of driving later at 70 miles an hour with several pretty long stretches of slowed by construction driving reached the next SC with 33 miles rated remaining.
Overall, I really enjoyed the trip and the charging stops were indeed a nice chance to relax a bit and a get a bite to eat or a grab a starbucks. However, my brother-in-law driving an ICE car beat us home by nearly two hours and a 4 1/2 hour ICE trip took us 6 1/2 hours. Since we were not in a rush, it was fine, but still kind of ticked me off and showed me why electrics still really can't be the only car you own, at least for most of us.
My P85D drove great and was very comfortable ride, I think quiet and less vibration vs ICE really makes a difference. My next trip, I may try to push the car a bit farther to try and skip a SC, by driving a bit slower. The offset is the charging does significantly slow the closer you get to max mile range, the miles added during the first 20 min or so of charging is impressive, so finding the optimal blance between charging stops still seems like a bit of an art.