Niagara Falls was not at the top of my list of places to see, but I was "in the neighborhood" and decided to drive over. I'm very glad I did.
You start to see the falls as you drive along this long road that follows the river (on the Canadian side). They have this great, long walkway that's like a park, with people from all over the world just hanging out. Parking is outrageous, but then walking around and looking as long as you want to is free.
When I got there, a huge rainbow rested over Horseshoe Falls, and then I saw a double rainbow as I looked over toward American Falls. The sound is the best part, that constant, thunderous crash of water. If you like white noise, here's a live webcam that has sound on it, although a little static-y.
I took lots of pictures; walk a few feet and see a different angle. I saw the end of the rainbow - both ends, as a matter of fact! There wasn't any pot of gold, but there was a lot of water. The waterfalls are cloud-makers, with a constant mist around them. I didn't mind a little wet, as long as I could keep the camera dry.
I walked and walked. The near section of town is uber-touristy, a lot like Myrtle Beach, S.C. with wax museums and haunted houses. I got some fish & chips and a beer before starting the walk back to the car. The rainbow was gone, a pink glow just leaving the falls as the sun set.