Most tour companies consider the 10:30/11:00 time slot to be the prime sunbeam tour. The best time to visit the canyons is mid-afternoon for the iconic light shafts you’ve see in images of this spot.
It’s a super simple walk through the canyon, less than a mile long! Lower Canyon requires climbing down a few ladders but is equally breathtaking. The Upper Canyon is the more ‘iconic’ one that you’ve likely seen images of.