Rishikesh: the town and the valley
Rishikesh is two places, and confusing them is why some people leave disappointed.
The town
Bridges, bells, shops, the crowd on the ghats as the light goes. The evening aarti is genuinely moving and genuinely crowded, and both of those are part of it. An afternoon of the high street is plenty for most people; a week of it is a lot.
The valley
Above and outside, it is forest, river noise and very little else. Cool air in the evening. Paths through trees. The river as a sound rather than a scene. People who love Rishikesh are almost always describing this part.
Stay in the second, visit the first
That is the whole recommendation. Go down for the bridges and the aarti, and come back up. The contrast is the experience — arriving back into quiet after the ghats at dusk is better than either on its own.
What to do up there
Walk. Forest paths are the thing guests most consistently underestimate. Sit by the water. Swim, if where you are staying has a pool on a terrace above the valley. Practise yoga if that is why you came, and do nothing whatsoever if it is not — the valley is just as good for people who came only to stop moving.
Rafting
Seasonal, and genuinely seasonal — the river does not always allow it. Ask whoever you are staying with and take the honest answer. Anybody who says yes in every month is not answering about the river.
When
Spring and autumn are the easy ones. Winter mornings are cold and beautiful. Summer is much better above the town than in it. In the monsoon the forest is spectacular, paths are slippery and the water sports stop.
Wildcrest is on a hillside above the river. More on staying near Rishikesh.