Just got back from Niagara Falls. Wow, what a great vacation! It was only 4 days, but felt like a week. Stayed at the Great Wolf Lodge a couple miles downstream from the falls. Didn't see any bike commuters (keeping it on topic, ya know). Surprisingly not that many bikes in the city, given the great cycling infrastructure. More pedestrians than anything else.
Thanks to everyone for the tips. Ended up riding a 40 mile loop over to Lock 3 on the Welland Canal on York and Queenston Roads. Then up to Lake Ontario on the MUP, across to Niagara-on-the-Lake on quiet roads, and then back to Niagara Falls. The one long hill, which I guess is the escarpment, was tough at the end of the ride. Niagara-on-the-Lake is a really nice town. Stopped at the Niagara Home Bakery mentioned by Altair 4 for a delicious energy break.
Also did two rides past the falls towards Lake Erie, which is really beautiful and quiet once you get out of the city.
I'd love to spend more time there just cycling, maybe riding the 100 mile loop. Here are a few pictures. Unfortunately the camera phone doesn't do justice to the beauty of the falls.
The falls
More falls
Ride towards Lake Erie
Lock 3 on the Welland Canal