There is Definatily more happening on the Canadian side.
I took a little trip last year w/ my fiancee' (I also managed to squeeze in a MA seminar in Buffalo

)!
It depends on what you are looking for, of course, but I don't recommend the "Big" Hotels. They are totally "touristed out" and way to expensive, and not romantic.
I would stay at a little bed in Breakfast in town, or at a hotel outside of Niagra, and drive in. Also...when you get in look for packaged deals on different attractions to save some bucks. On the Canadian side, definatily get day passes for the trolly, otherwise you'll spend your whole time walking instead of sight-seeing.
I also suggest looking for nice dinner places outside of Niagra, like in Buffalo or other areas of Canada.
Niagera is a great time, but it is WAY too touristy. It can be very crowded at times (although this time of year will be good), and overpriced. But there are a lot of cool things to do that aren't "in town" too, particularly food places. So, I would balance out your time by getting your days started early, doing things at odd times as opposed to 'going with the crowd' (like instead of lunch at noon when everybody else has lunch, for example, eat before 11 or after 1:30), and trying some activities outside of Niagera. I suggest checking out tourest info online, I found that to be helpful.
I am sure you'll have fun! :wavey: