My wife and I just finished driving from Los Angeles to Connecticut, primarily on the SuperCharger Trail. I'm very glad we did it, and doing it in a Tesla is about 10 times better than any ICE. To say otherwise is to speak from ignorance. To stop every 2 or 3 hours is not a bad thing, except that we ate way too much junk food. Our fault, should have planned better and been smarter.
I want to summarize some of the salient points for future travelers. I also want to thank the forums at TeslaMotors.com and TeslaMotorsClub.com plus @SamO, @Cottonwood, @stevezzz, EVTripPlanner.com and TeslaWiki.net and many others for pioneering the trail and giving so much good information to us.
1) For us, it was much better to drive fast and stop more often. East from Blanding, UT there's a LOT of superchargers. You can drive as fast as you want, NOT need to do a range charge (in an 85), and still have plenty of juice and no range anxiety. We did not do a single range charge east of Colorado, did not experience any range anxiety, and drove as fast as we wanted. And in a few cases, we even passed right by superchargers without stopping.
2) The 3 major things that affect range are: speed, speed and speed. Slowing even from 70 to 65 makes a big difference. 75 to 65 is a real big difference. And if you're worried, drive 55-60. If you have any range anxiety at all, just drive 65 and keep comparing your range miles with the miles left in the navigation. You'll know if/when you can speed up.
3) After speed, the elevation change and outside temperature also can affect range. Speed you can change. Changing elevation and temperature requires superpowers.
4) Cabin electricity has very little effect on range. Heat it, cool it, listen to stuff, etc. We even regularly charged our phones and tablets. Climate control has more effect than these other things, but it's still pretty insignificant. Think how much juice is required to propel a 4600 pound car (before occupants, luggage, etc.) at freeway speeds?
5) Outside California, the number of Tesla's drops dramatically until you reach the East Coast. Between Los Angeles and Colorado, we never saw more than one Tesla at a Supercharger. And from Silverthorne, CO to Cranberry, PA I only saw one other person charging.
6) EVTripPlanner.com is an invaluable tool on road trips, particularly where elevation is involved.
7) There are very useful websites, but through a lot of the middle of the country, we did not have internet coverage. We have Sprint. Maybe it's different if you have Verizon or something else.
8) The changes to the Navigation system make finding and using Superchargers much easier. The SC tab makes it easy to find the next one. The checkered flag is pretty tight on locations, so just zoom in and it will direct you to the correct part of the parking lot.
9) We left the SuperCharger trail twice. Kingman, AZ to Blanding, UT and also Somerset, PA to Hamilton Township, NJ. Both of those cut off significant mileage and/or provided great sightseeing. Almost all RV campgrounds (and there's a ton of them) have Nema 14-50 chargers available. Some are very EV friendly. Some are not. YMMV so always call first. You'll only get 18-32 range miles per hour of charging, but if you can charge overnight or just need a little boost, it can work out very well.
10) Off the Supercharger Trail, we went from Kingman to Blanding and charged at the Grand Canyon Trailer Park. Yavapai Lodge/Cafe is a short walk away. But make sure you have a reservation for a space to charge, and make sure your reservation is prominently displayed on the dashboard. We were disconnected a few minutes after we left the car (by persons or animals unknown) and had to hang around for 5 hours to get enough charge to continue.
11) We also went from Somerset, PA to Hamilton Township, NJ, stopping overnight at the Fairfield Inn in Hershey, PA. They have two public Level 2 J-1772's that charge at 18 mph and cost $1.24/hour. Perfect for an overnight stay.
12) Obviously hotels on the road vary. Here's our experience, with the first being best:
Fairfield Inn, Hershey, PA
Best Western Canyonlands, Moab, UT
Little America Hotel, Cheyenne, WY (our best meal on the trip)
Hampton Inn, Onalaska, WI (La Crosse SC)
Range Country Inn, Murdo, SD
Yavapai Lodge, Grand Canyon, AZ
Ramada Inn, Angola, IN