You will have a better view of the Falls from the Canadian side, and the area is better developed. There is decent hiking on the US side, but there is very little to do in Niagara Falls, NY. To be frank...it's a dump. There's a pretty nice casino, the state park (which is fine - but again, you'll get better views from the Canadian side), and some standard walking/hiking trails, but nothing much else. Goat Island, Bridal Veil Falls, Three Sisters Islands, Terrapin Point, they're all beautiful as part of the state park and worth a walk, but hardly something that's gonna blow you away if you're coming from out of town.
Niagara Falls, ON is an absolute tourist trap, but is a much nicer, well-developed area. Again, the views are better from Canada, because you can get a full panorama view of both major falls - the "American Falls" which are the impressive but comparably ho-hum ones, and the "Canadian Falls" aka "Horseshoe Falls".
You can do boat tours. Hornblower runs the Canadian side, and Maid of the Mist runs the US side. I haven't been on the Canadian tour but I assume they're likely very similar. It is likely that you will get wet if you get anywhere near the Falls themselves, and you will DEFINITELY get wet on those boat tours. Even the mist can be pretty strong, just be aware. The wind will likely be substantially stronger and temps a few degrees colder than the area of the Western NY and Southern ON area, but if you're going in the middle of summer it should be great.
Niagara-on-the-Lake, ON is beautiful and you should check it out if you're looking for quaint shops. It is a very charming B&B community a short drive north of the falls. Nice walkable main street, plenty of little shops and restaurants, beautiful old homes....really a picturesque little place. Also right in wine country, plenty of wineries around if that's your thing.
If you're into history and still in the US, I've always thought
Fort Niagara is pretty cool. Was part of the fortifications during the French and Indian War and War of 1812. Now it's a historic landmark and museum. Not a bad way to waste an hour or two if you like military history.