Went to Prineville two summers ago and stayed over 4th of July weekend at Crook County RV Park Crook County Parks and Recreation District
Pretty nice park but it's still about 50 miles to Painted Hills unit and even farther to Sheep Rock unit but both are a photographer's dream. You can go back many times and they won't look the same because of time of day, cloud cover, etc. My son and I hiked for hours and filled up multiple memory cards.
Also west of Prineville in Terrebonne, hiking Smith Rock to see Monkey Face is awesome.