Although viewing Niagara Falls from both sides of the border present you with breathtaking views, there is only one side where you are guaranteed to see a rainbow every time!
When planning your trip, make sure to view the Horseshoe Falls from the location highlighted here. Not only does it provide you with the closest view of the Horseshoe Falls (aka the Canadian Falls) from the Canadian side of the border, but it also offers the best photo location.
This specific location also provides you with the best vantage point to always see a rainbow (if the weather cooperates). You are literally guaranteed to see a rainbow viewing Niagara Falls from Canada!
FUN FACT: the Horseshoe Falls spans from the U.S. side of the border to the Canadian side. This is one of two waterfalls in the world that touch two different countries (the other being Iguazu Falls which touch Brazil and Argentina).