Don't think there are any. I was going to say part of the stretch of counties between San Francisco & Pollock Pines, but then I remembered that Xahar has also been that way.
Indeed I have. Pretty country. I don't know whether I've been anywhere in the United States that nobody else has been to; I've been to some remote counties in eastern Idaho, but they're on the road from Salt Lake City to Yellowstone. Abroad, I don't think anyone else has been to Dhaka, though Lewis might have. Presumably others have been to Singapore; certainly others have been to Hong Kong and Bangkok.