The single biggest variable here is foliage, and most visitors arrive in exactly the wrong month for the view.
June to September. The canopy closes. You get a green corridor with fragments of river through it, pleasant enough but not the view in the history books. Early morning is better than midday because the light comes down the gorge rather than straight into the lens.
Mid to late October. Colour on both ridges, and the busiest fortnight of the year on these steps. Come on a weekday or on the first shuttle.
November to March. The best months, and almost nobody says so. Leaves down, sightlines open, the tilted rock in the opposite cliff visible, the rivers full and loud. Ice on the steps is the catch, and microspikes in January are not an overreaction.
Last hour of daylight, any season. The gorge runs south-west, so late sun comes straight up it. This is the reason photographers keep returning, and it is worth structuring a day around: lower town in the morning, the heights in the middle, this at the end.
Remember that the last shuttle back to Cavalier Heights leaves the lower town at seven in summer and half past five in winter.