If you do go to the falls, you want to be on the Canadian side. There’s no good view anywhere in New York due to the bend in the river. When you’re on the Canadian side, you can stand on a walkway and face the falls. That’s the impressive view.
The Maid of the Mist and the tunnel under the falls are cool, but now that I’ve done these things once, I probably wouldn’t do them again if I go back, unless I’m accompanying someone who really wants to do these things.
If you like to hike, there are trails down into the gorge that aren’t widely publicized. You start at a park (labeled Niagara Glen Nature Reserve on Google Maps) a couple of miles downriver from the whirlpool and you can hike all the way to the whirlpool, sit on a rock 20 feet from the whirlpool. But if there are any kind of icy conditions when you’re there, don’t do this. The hike is a little tough and there’s no easy way out if you hurt yourself. I’m not a nature-type person, but I’ve been to Niagara Falls 7 times, and I’ve done this the last 6 times I’ve been there.
There are a lot of tourist traps around there…the Clifton Hill area is packed with all sorts of tacky tourist attractions, and a few cool ones like Hard Rock Cafe and Ripley’s Believe it or Not (ok, maybe these are tacky, but I liked 'em).
If you spend any amount of time there, travel away from the chain-type places in the tourist area for meals and you’ll spend half the money. If you like diner type food, there’s a place on Lundy’s Lane, almost to the QEW, called The Flying Saucer that’s kind of greasy, relatively cheap, but serves breakfast any time of day among other things. The building is shaped like a giant flying saucer. (This may be tacky too, but once again, I liked it and never got bad food or service there.)
Finally, I’ve never been to Niagara Falls and not found a huge Cruise Night on a weekend. I’m not sure if they do it during the coldest part of the winter, but if you like old cars, this is something to check out. I saw some car models that were exclusive to Canada in 60s and earlier that you’re not likely to see in the U.S.
There are a lot of things to do in Niagara Falls that I never would’ve found on my own, but I have friends who live up there. I like to find things that the flocks of tourists aren’t doing. If I hadn’t had a local giving me pointers, I probably wouldn’t have felt any need to go back again.