If looking for high end/luxury and the best overall location perched right over the falls...look no further than the NF Marriott Fallsview....stunning lobby, every room a view of the falls, restaurant top-notch, and they offer very interesting 2-night packages and have family suites (1 & 2-bedroom) etc...
The first time I stayed, I arrived at 10 pm or so, walked into a room with floor-to-ceiling windows and a drop-dead view of the falls (all rooms have this)....with the lights on the falls it was a magical, dare-I-say Disney-like experience!
For 13 years I have been a Marriott "Platinum" (very frequent stayer) and I consider this hotel to be in the top 20 of that chain!
By the way, Canada has 2 other absolutely stunning Marriott properties...the Eaton Center Marriott in Toronto and the new spectacular Vancouver Pinnacle Marriott...love em to no end!
Hope this helps!