Water, fall?
Niagara is basically a mini Las Vegas, with a central strip featuring brightly lit, loudly advertised attractions looking down towards the crushing water. Helicopters from the tours spiral over head while the Maid of the Mist churns below, soaking another horde of passengers.
Going straight from the helicopter to the Maid provides a great contrast: on one, you are hung tantalisingly over the falls, seeing them from a distance as they pour over the cliff. Then, boarding the Maid you are presented with a flattering blue waterproof, and told you mind your step on the slippery deck. As the large tug moves slowly, certainly towards the water, people start to hide their cameras inside their waterproof tops as the realisation dawns on them that they are going to be in the middle of the Canadian falls (the larger, horse-shoe shaped one). The spray starts to break over the occupants and deck, the visibility drops to about one meter, the sound drowning out the cries of children complaining "Mom I'm wet!"
Pulling back from the boat puts you on Table Rock, from which you can get a view that's halfway between the helicopter and the Maid (and watch as the occasional Japanese tourist scrambles over the fence to take a better photo).
The falls themselves are mostly indescribable: the power, the volume of water, the noise, it just doesn't translate to words. Photos pale in comparison. To really understand the obsession with the falls you have to visit yourself, get drenched, get drunk, and cheat in a maze designed for three-year-olds...