The Canadian side is said to have a much better view of the Falls, also it is more touristy (if you like that). I live about 30min away, and avoid all the touristy areas especially at this time of year.
The Maid of the Mist is only on the US side now. The Canadian version is now called Hornblower Niagara Cruises. It's probably very similar.
The bus service is called WEGO. There are places that you can get free parking and then take the WEGO bus to the Falls and other attractions.
Also your American dollar is worth about 1.25 Canadian these days, and many Canadian retailers will accept US cash. Credit cards are, of course, accepted. I think you would probably get the best exchange rate at a Canadian bank.
There is an entry on Niagara Falls on Wikitravel that might give you some ideas.
https://en.wikivoyage.org/wiki/Niagara_Falls_(Ontario)
Dan mentioned the wineries, and there are quite a number around Niagara-on-the-Lake. I haven't visited them all, but Inniskillin was the first of the "better" Canadian wineries, and Reif is my favourite. These two are near each other on the River Road just south of the village of N-o-t-L.
If transportation intrigues you, try to visit the Welland Canal. Hopefully, there will be some ships in transit when you are there. The Lock 3 Museum is probably the best spot unless you're a serious photographer, in which case ask, and I'll give you some suggestions.
Steve