Johnston Canyon is described by hiking sites and guidebooks as the busiest hike in Banff - from my experience this seems to be a very accurate statement.
I've done this hike twice in the past few years both times on weekends, once in July and once in August. Due to the overwhelming crowds I'm not planning on going back anytime soon. We have a dog and two kids under three - this hike is short but was one of our most challenging due to people not terrain. If we didn't have a dog or kids I think it would be a more pleasant adventure. We decided to do the hike this year as we were camping in the Johnston Canyon Campground, it's an "easy" walk for the kids and you can walk to the trail head from the campground.
Johnston Canyon hike to the first falls is 2.7km round trip and 5.8km round trip to the ink pots. Further trail details can be found on the Town of Banff site.
The hike is unique in that you are actually hiking in the canyon along walkways that have been built. Without these walkways the terrain would inaccessible. I think this is awesome and an interesting experience. The pathways are narrow and have fences. I found walking with a two year old to be nerve racking as small children can still fall through the fence if bumped or trip.
It is not always possible to visit places off season, early morning in the evening but if you don't like crowds or want to experience Johnston Canyon without walking in a single file with hundreds of people you really need to plan your timing.
It's always nice to go on a hike at least once...but sometimes once is enough.