@J Mack, I drove through Council/Riggins/Grangeville in 2003 on my way to Spokane. Pretty country.
@RUSH55 as a (former) Las Vegas native who lives in Austin now, I completely agree.
Death Valley in the summer is a pig cooling system stress test.
The *average* temp in July was 107.4 degrees Fahrenheit, which is the hottest month, anywhere, on Earth, ever.
Many days had a high temp that exceeded 120F. The Furnace Creek Visitor Center recorded a temperature of 127 F on four days in July.
Obviously, as originally suggested, we'd have to change dates to do Death Valley or the Mohave Road. Only a fool would be out there in July, although they do run a mid-summer ultra marathon there. Probably late March/early April would be optimum. We've camped there in March and experienced near freezing overnight temps. Hard to beat the area for lots to do on accessible trails. An earlier outing would also offer the opportunity for those who wished to join JMack in Idaho mid-June. Alternatively, lots of history and many interesting side trips along the Mohave Road from the Colorado River to almost Barstow (look it up), which could but doesn't need to be a straight line drive, and it could easily fit our usual 3-4 day schedule.
No intent to argue any of this...just throwing out options. We'll likely be there whatever the ultimate decision.