We visited the park on April 28, 2018 and stayed there for two nights.
The best sunrise location was at the end of Door Trail. Sunrise at Big Badlands overlook was also nice.
Good sunset locations were Bigfoot Pass Overlook, Conata Basin Overlook and Yellow Mounds Overlook. Passing Yellow Mounds Overlook there were some very colorful yellowish land formations were worth exploring.
We also hiked Castle Trail and Medicine Root Trail. Because those trails were far away from the formations, I was not impressed. I would rather explore the hills along the road than hiking those trails. But for completeness of the visit, we hiked all of them.
Sunrise at Door Trail
Sunset at Bigfoot Pass Overlook
Surise at Big Badlands Overlook
Storm Coming at Bigfoot Pass Overlook
Sunset at Conata Basin Overlook
Sunrise at Door Trail
Mountain Goat
Land Formation around Yellow Mounds Overlook
Land Formation around Yellow Mounds Overlook
Sunset at Yellow Mounds Overlook
Land Formation around Yellow Mounds Overlook