I recently returned from a trip to Death Valley. Here are a few of the places I visited that provided good photo ops and times of the day I thought were good for photography.
Badwater: sunrise (catch alpen glow on peaks of Panamint Mountains)
Dantes View: soon after Sunrise (great views along the trail)
Artist Drive: about an hour after sunrise, and sunset
Golden Cyn: about 1/2hr before sunset (especially about a mile up the trail, bring a flashlight)
Zabriskie Point: sunrise(best) and sunset
Dunes near Stovepipe Wells: Sunrise and Sunset (for dunes with minimal footprints, drive about 1/2 mile north of the dunes parking lot then walk about 0.5-1 mile along north edge of dune filed, take a gps reading at your car to make it easy to find your way back)
Note: Sunset comes early to Death Valley due to the Panamint Mountains
I've also had good luck at Badwater (actually just a bit south) around sunset, especially if there are interesting clouds over the Panamints. Also, canyons like Golden Canyon can often be decent a bit later in the morning and/or earlier in the afternoon since light doesn't go directly down into them.
It may surprise people to find that some locations provide some interesting options at non-standard times. Last time I was at Zabriskie I first shot at the usual dawn hour, but I spotted a small element in the landscape there that I thought might work later in the morning, returned later (perhaps around 10:00 a.m.), and came away with something I like. (Not the standard view.)
When I go to the Racetrack I usually plan to stay overnight and shoot early/late. However, I find that the Grandstand is interesting to shoot in the mid- to late-afternoon time frame.
Dan